diff --git a/usermods/usermod_v2_four_line_display_ALT/usermod_v2_four_line_display_ALT.h b/usermods/usermod_v2_four_line_display_ALT/usermod_v2_four_line_display_ALT.h
index a4e6291b..afc1bb63 100644
--- a/usermods/usermod_v2_four_line_display_ALT/usermod_v2_four_line_display_ALT.h
+++ b/usermods/usermod_v2_four_line_display_ALT/usermod_v2_four_line_display_ALT.h
@@ -1,11 +1,16 @@
 #pragma once
 
 #include "wled.h"
+#undef U8X8_NO_HW_I2C // borrowed from WLEDMM: we do want I2C hardware drivers - if possible
 #include <U8x8lib.h> // from https://github.com/olikraus/u8g2/
 #include "4LD_wled_fonts.c"
 
+#ifndef FLD_ESP32_NO_THREADS
+  #define FLD_ESP32_USE_THREADS  // comment out to use 0.13.x behviour without parallel update task - slower, but more robust. May delay other tasks like LEDs or audioreactive!!
+#endif
+
 //
-// Insired by the usermod_v2_four_line_display
+// Inspired by the usermod_v2_four_line_display
 //
 // v2 usermod for using 128x32 or 128x64 i2c
 // OLED displays to provide a four line display
@@ -88,9 +93,11 @@ typedef enum {
 
 
 class FourLineDisplayUsermod : public Usermod {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   public:
     FourLineDisplayUsermod() { if (!instance) instance = this; }
     static FourLineDisplayUsermod* getInstance(void) { return instance; }
+#endif
 
   private:
 
@@ -215,9 +222,7 @@ class FourLineDisplayUsermod : public Usermod {
     void loop();
 
     //function to update lastredraw
-    void updateRedrawTime() {
-      lastRedraw = millis();
-    }
+    inline void updateRedrawTime() { lastRedraw = millis(); }
 
     /**
      * Redraw the screen (but only if things have changed
@@ -352,10 +357,13 @@ const char FourLineDisplayUsermod::_showSeconds[]     PROGMEM = "showSeconds";
 const char FourLineDisplayUsermod::_busClkFrequency[] PROGMEM = "i2c-freq-kHz";
 const char FourLineDisplayUsermod::_contrastFix[]     PROGMEM = "contrastFix";
 
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
 FourLineDisplayUsermod *FourLineDisplayUsermod::instance = nullptr;
+#endif
 
 // some displays need this to properly apply contrast
 void FourLineDisplayUsermod::setVcomh(bool highContrast) {
+  if (type == NONE || !enabled) return;
   u8x8_t *u8x8_struct = u8x8->getU8x8();
   u8x8_cad_StartTransfer(u8x8_struct);
   u8x8_cad_SendCmd(u8x8_struct, 0x0db); //address of value
@@ -364,6 +372,7 @@ void FourLineDisplayUsermod::setVcomh(bool highContrast) {
 }
 
 void FourLineDisplayUsermod::startDisplay() {
+  if (type == NONE || !enabled) return;
   lineHeight = u8x8->getRows() > 4 ? 2 : 1;
   DEBUG_PRINTLN(F("Starting display."));
   u8x8->setBusClock(ioFrequency);  // can be used for SPI too
@@ -590,7 +599,7 @@ void FourLineDisplayUsermod::connected() {
  * Da loop.
  */
 void FourLineDisplayUsermod::loop() {
-#ifndef ARDUINO_ARCH_ESP32
+#if !(defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS))
   if (!enabled || strip.isUpdating()) return;
   unsigned long now = millis();
   if (now < nextUpdate) return;
@@ -716,6 +725,11 @@ void FourLineDisplayUsermod::redraw(bool forceRedraw) {
 }
 
 void FourLineDisplayUsermod::updateBrightness() {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   knownBrightness = bri;
   if (overlayUntil == 0) {
     lockRedraw = true;
@@ -728,6 +742,11 @@ void FourLineDisplayUsermod::updateBrightness() {
 }
 
 void FourLineDisplayUsermod::updateSpeed() {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   knownEffectSpeed = effectSpeed;
   if (overlayUntil == 0) {
     lockRedraw = true;
@@ -740,6 +759,11 @@ void FourLineDisplayUsermod::updateSpeed() {
 }
 
 void FourLineDisplayUsermod::updateIntensity() {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   knownEffectIntensity = effectIntensity;
   if (overlayUntil == 0) {
     lockRedraw = true;
@@ -752,6 +776,11 @@ void FourLineDisplayUsermod::updateIntensity() {
 }
 
 void FourLineDisplayUsermod::drawStatusIcons() {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   uint8_t col = 15;
   uint8_t row = 0;
   lockRedraw = true;
@@ -775,6 +804,11 @@ void FourLineDisplayUsermod::setMarkLine(byte newMarkLineNum, byte newMarkColNum
 
 //Draw the arrow for the current setting beiong changed
 void FourLineDisplayUsermod::drawArrow() {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   lockRedraw = true;
   if (markColNum != 255 && markLineNum !=255) drawGlyph(markColNum, markLineNum*lineHeight, 21, u8x8_4LineDisplay_WLED_icons_1x1);
   lockRedraw = false;
@@ -783,6 +817,11 @@ void FourLineDisplayUsermod::drawArrow() {
 //Display the current effect or palette (desiredEntry) 
 // on the appropriate line (row). 
 void FourLineDisplayUsermod::showCurrentEffectOrPalette(int inputEffPal, const char *qstring, uint8_t row) {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
+  unsigned long now = millis();
+  while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+  if (drawing || lockRedraw) return;
+#endif
   char lineBuffer[MAX_JSON_CHARS];
   if (overlayUntil == 0) {
     lockRedraw = true;
@@ -851,9 +890,11 @@ void FourLineDisplayUsermod::showCurrentEffectOrPalette(int inputEffPal, const c
 bool FourLineDisplayUsermod::wakeDisplay() {
   if (type == NONE || !enabled) return false;
   if (displayTurnedOff) {
+  #if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
     unsigned long now = millis();
-    while (drawing && millis()-now < 250) delay(1); // wait if someone else is drawing
-    if (drawing) return false;
+    while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
+    if (drawing || lockRedraw) return false;
+  #endif
     lockRedraw = true;
     clear();
     // Turn the display back on
@@ -870,9 +911,11 @@ bool FourLineDisplayUsermod::wakeDisplay() {
  * Used in Rotary Encoder usermod.
  */
 void FourLineDisplayUsermod::overlay(const char* line1, long showHowLong, byte glyphType) {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   unsigned long now = millis();
   while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
-  if (drawing) return;
+  if (drawing || lockRedraw) return;
+#endif
   lockRedraw = true;
   // Turn the display back on
   if (!wakeDisplay()) clear();
@@ -895,9 +938,11 @@ void FourLineDisplayUsermod::overlay(const char* line1, long showHowLong, byte g
  * Clears the screen and prints.
  */
 void FourLineDisplayUsermod::overlayLogo(long showHowLong) {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   unsigned long now = millis();
   while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
-  if (drawing) return;
+  if (drawing || lockRedraw) return;
+#endif
   lockRedraw = true;
   // Turn the display back on
   if (!wakeDisplay()) clear();
@@ -957,9 +1002,11 @@ void FourLineDisplayUsermod::overlayLogo(long showHowLong) {
  * Used in Auto Save usermod
  */
 void FourLineDisplayUsermod::overlay(const char* line1, const char* line2, long showHowLong) {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   unsigned long now = millis();
   while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
-  if (drawing) return;
+  if (drawing || lockRedraw) return;
+#endif
   lockRedraw = true;
   // Turn the display back on
   if (!wakeDisplay()) clear();
@@ -979,9 +1026,11 @@ void FourLineDisplayUsermod::overlay(const char* line1, const char* line2, long
 }
 
 void FourLineDisplayUsermod::networkOverlay(const char* line1, long showHowLong) {
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   unsigned long now = millis();
   while (drawing && millis()-now < 125) delay(1); // wait if someone else is drawing
-  if (drawing) return;
+  if (drawing || lockRedraw) return;
+#endif
   lockRedraw = true;
 
   String line;
@@ -1098,7 +1147,7 @@ bool FourLineDisplayUsermod::handleButton(uint8_t b) {
 #define ARDUINO_RUNNING_CORE 1
 #endif
 void FourLineDisplayUsermod::onUpdateBegin(bool init) {
-#ifdef ARDUINO_ARCH_ESP32
+#if defined(ARDUINO_ARCH_ESP32) && defined(FLD_ESP32_USE_THREADS)
   if (init && Display_Task) {
     vTaskSuspend(Display_Task);   // update is about to begin, disable task to prevent crash
   } else {
diff --git a/usermods/usermod_v2_rotary_encoder_ui_ALT/usermod_v2_rotary_encoder_ui_ALT.h b/usermods/usermod_v2_rotary_encoder_ui_ALT/usermod_v2_rotary_encoder_ui_ALT.h
index a5506e77..b1674951 100644
--- a/usermods/usermod_v2_rotary_encoder_ui_ALT/usermod_v2_rotary_encoder_ui_ALT.h
+++ b/usermods/usermod_v2_rotary_encoder_ui_ALT/usermod_v2_rotary_encoder_ui_ALT.h
@@ -57,6 +57,10 @@
   #define PCF8574_ADDRESS 0x20  // some may start at 0x38
 #endif
 
+#ifndef PCF8574_INT_PIN
+  #define PCF8574_INT_PIN -1    // GPIO connected to INT pin on PCF8574
+#endif
+
 // The last UI state, remove color and saturation option if display not active (too many options)
 #ifdef USERMOD_FOUR_LINE_DISPLAY
  #define LAST_UI_STATE 11
@@ -125,6 +129,21 @@ static int re_qstringCmp(const void *ap, const void *bp) {
 }
 
 
+static volatile uint8_t pcfPortData = 0;                // port expander port state
+static volatile uint8_t addrPcf8574 = PCF8574_ADDRESS;  // has to be accessible in ISR
+
+// Interrupt routine to read I2C rotary state
+// if we are to use PCF8574 port expander we will need to rely on interrupts as polling I2C every 2ms
+// is a waste of resources and causes 4LD to fail.
+// in such case rely on ISR to read pin values and store them into static variable
+static void IRAM_ATTR i2cReadingISR() {
+  Wire.requestFrom(addrPcf8574, 1U);
+  if (Wire.available()) {
+    pcfPortData = Wire.read();
+  }
+}
+
+
 class RotaryEncoderUIUsermod : public Usermod {
 
   private:
@@ -186,7 +205,7 @@ class RotaryEncoderUIUsermod : public Usermod {
     bool enabled;
 
     bool usePcf8574;
-    uint8_t addrPcf8574;
+    int8_t pinIRQ;
 
     // strings to reduce flash memory usage (used more than twice)
     static const char _name[];
@@ -199,6 +218,7 @@ class RotaryEncoderUIUsermod : public Usermod {
     static const char _applyToAll[];
     static const char _pcf8574[];
     static const char _pcfAddress[];
+    static const char _pcfINTpin[];
 
     /**
      * readPin() - read rotary encoder pin value
@@ -254,7 +274,7 @@ class RotaryEncoderUIUsermod : public Usermod {
       , initDone(false)
       , enabled(true)
       , usePcf8574(USE_PCF8574)
-      , addrPcf8574(PCF8574_ADDRESS)
+      , pinIRQ(PCF8574_INT_PIN)
     {}
 
     /*
@@ -356,15 +376,7 @@ class RotaryEncoderUIUsermod : public Usermod {
  */
 byte RotaryEncoderUIUsermod::readPin(uint8_t pin) {
   if (usePcf8574) {
-    byte _data = 0;
-    if (pin < 8) {
-      Wire.requestFrom(addrPcf8574, 1U);
-      if (Wire.available()) {
-        _data = Wire.read();
-        _data = (_data>>pin) & 1;
-      }
-    }
-    return _data;
+    return (pcfPortData>>pin) & 1;
   } else {
     return digitalRead(pin);
   }
@@ -460,14 +472,25 @@ void RotaryEncoderUIUsermod::setup()
 {
   DEBUG_PRINTLN(F("Usermod Rotary Encoder init."));
 
-  if (!usePcf8574) {
+  if (usePcf8574) {
+    if ((i2c_sda == i2c_scl && i2c_sda == -1) || pinA<0 || pinB<0 || pinC<0) {
+      DEBUG_PRINTLN(F("I2C and/or PCF8574 pins unused, disabling."));
+      enabled = false;
+      return;
+    } else {
+      if (pinIRQ >= 0 && pinManager.allocatePin(pinIRQ, false, PinOwner::UM_RotaryEncoderUI)) {
+        attachInterrupt(pinIRQ, i2cReadingISR, CHANGE); // RISING, FALLING, CHANGE, ONLOW, ONHIGH
+        DEBUG_PRINTLN(F("Interrupt attached."));
+      } else {
+        DEBUG_PRINTLN(F("Unable to allocate interrupt pin, disabling."));
+        pinIRQ = -1;
+        enabled = false;
+        return;
+      }
+    }
+  } else {
     PinManagerPinType pins[3] = { { pinA, false }, { pinB, false }, { pinC, false } };
     if (!pinManager.allocateMultiplePins(pins, 3, PinOwner::UM_RotaryEncoderUI)) {
-      // BUG: configuring this usermod with conflicting pins
-      //      will cause it to de-allocate pins it does not own
-      //      (at second config)
-      //      This is the exact type of bug solved by pinManager
-      //      tracking the owner tags....
       pinA = pinB = pinC = -1;
       enabled = false;
       return;
@@ -479,12 +502,6 @@ void RotaryEncoderUIUsermod::setup()
     pinMode(pinA, USERMOD_ROTARY_ENCODER_GPIO);
     pinMode(pinB, USERMOD_ROTARY_ENCODER_GPIO);
     pinMode(pinC, USERMOD_ROTARY_ENCODER_GPIO);
-  } else {
-    if ((i2c_sda == i2c_scl && i2c_sda == -1) || pinA<0 || pinB<0 || pinC<0) {
-      DEBUG_PRINTLN(F("Pins unused, disabling."));
-      enabled = false;
-      return;
-    }
   }
 
   loopTime = millis();
@@ -536,7 +553,7 @@ void RotaryEncoderUIUsermod::loop()
     currentEffectAndPaletteInitialized = false;
   }
 
-  if (currentTime >= (loopTime + 20)) // 20ms since last check of encoder = 50Hz
+  if (currentTime >= (loopTime + 2)) // 2ms since last check of encoder = 500Hz
   {
     bool buttonPressed = !readPin(pinC); //0=pressed, 1=released
     if (buttonPressed) {
@@ -645,8 +662,6 @@ void RotaryEncoderUIUsermod::loop()
       }
     }
     Enc_A_prev = Enc_A;     // Store value of A for next time
-    DEBUG_PRINTF("Inputs: A:%d B:%d SW:%d\n", (int)Enc_A, (int)Enc_B, (int)!buttonPressed);
-
     loopTime = currentTime; // Updates loopTime
   }
 }
@@ -1051,6 +1066,7 @@ void RotaryEncoderUIUsermod::addToConfig(JsonObject &root) {
   top[FPSTR(_applyToAll)] = applyToAll;
   top[FPSTR(_pcf8574)]    = usePcf8574;
   top[FPSTR(_pcfAddress)] = addrPcf8574;
+  top[FPSTR(_pcfINTpin)]  = pinIRQ;
   DEBUG_PRINTLN(F("Rotary Encoder config saved."));
 }
 
@@ -1074,6 +1090,7 @@ bool RotaryEncoderUIUsermod::readFromConfig(JsonObject &root) {
   int8_t newDTpin  = top[FPSTR(_DT_pin)]  | pinA;
   int8_t newCLKpin = top[FPSTR(_CLK_pin)] | pinB;
   int8_t newSWpin  = top[FPSTR(_SW_pin)]  | pinC;
+  int8_t newIRQpin = top[FPSTR(_pcfINTpin)] | pinIRQ;
   bool   oldPcf8574 = usePcf8574;
 
   presetHigh = top[FPSTR(_presetHigh)] | presetHigh;
@@ -1097,8 +1114,15 @@ bool RotaryEncoderUIUsermod::readFromConfig(JsonObject &root) {
   } else {
     DEBUG_PRINTLN(F(" config (re)loaded."));
     // changing parameters from settings page
-    if (pinA!=newDTpin || pinB!=newCLKpin || pinC!=newSWpin) {
-      if (!oldPcf8574) {
+    if (pinA!=newDTpin || pinB!=newCLKpin || pinC!=newSWpin || pinIRQ!=newIRQpin) {
+      if (oldPcf8574) {
+        if (pinIRQ >= 0) {
+          detachInterrupt(pinIRQ);
+          pinManager.deallocatePin(pinIRQ, PinOwner::UM_RotaryEncoderUI);
+          DEBUG_PRINTLN(F("Deallocated old IRQ pin."));
+        }
+        pinIRQ = newIRQpin;
+      } else {
         pinManager.deallocatePin(pinA, PinOwner::UM_RotaryEncoderUI);
         pinManager.deallocatePin(pinB, PinOwner::UM_RotaryEncoderUI);
         pinManager.deallocatePin(pinC, PinOwner::UM_RotaryEncoderUI);
@@ -1115,7 +1139,7 @@ bool RotaryEncoderUIUsermod::readFromConfig(JsonObject &root) {
     }
   }
   // use "return !top["newestParameter"].isNull();" when updating Usermod with new features
-  return !top[FPSTR(_pcf8574)].isNull();
+  return !top[FPSTR(_pcfINTpin)].isNull();
 }
 
 
@@ -1130,3 +1154,4 @@ const char RotaryEncoderUIUsermod::_presetLow[]  PROGMEM = "preset-low";
 const char RotaryEncoderUIUsermod::_applyToAll[] PROGMEM = "apply-2-all-seg";
 const char RotaryEncoderUIUsermod::_pcf8574[]    PROGMEM = "use-PCF8574";
 const char RotaryEncoderUIUsermod::_pcfAddress[] PROGMEM = "PCF8574-address";
+const char RotaryEncoderUIUsermod::_pcfINTpin[]  PROGMEM = "PCF8574-INT-pin";