diff --git a/src/main/kotlin/razorvine/c64emu/c64Main.kt b/src/main/kotlin/razorvine/c64emu/c64Main.kt
index b312dcd..224bc7e 100644
--- a/src/main/kotlin/razorvine/c64emu/c64Main.kt
+++ b/src/main/kotlin/razorvine/c64emu/c64Main.kt
@@ -245,6 +245,10 @@ class C64Machine(title: String) : IVirtualMachine {
         // this should result in ~1 Mhz cpu speed
         val timer = java.util.Timer("cpu-cycle", true)
         timer.scheduleAtFixedRate(0, 1000L/VicII.framerate) {
+//            if(cpu.isLooping) {
+//                // cpu is jump looping, could do some sleeping here perhaps
+//                // but should still consider irqs occurring in the meantime...
+//            }
             if (!paused) {
                 try {
                     while (vic.vsync) step()
diff --git a/src/main/kotlin/razorvine/ksim65/Cpu6502.kt b/src/main/kotlin/razorvine/ksim65/Cpu6502.kt
index 29d20f1..4521ad8 100644
--- a/src/main/kotlin/razorvine/ksim65/Cpu6502.kt
+++ b/src/main/kotlin/razorvine/ksim65/Cpu6502.kt
@@ -98,6 +98,11 @@ open class Cpu6502 : BusComponent() {
         protected set
     var instrCycles: Int = 0
         protected set
+    val isLooping: Boolean get() {
+        // jump loop detection
+        return (previousOpcodeAddress == currentOpcodeAddress) && !(pendingNMI || pendingIRQ)
+    }
+    private var previousOpcodeAddress: Address = 0xffff
 
     lateinit var currentInstruction: Instruction
 
@@ -263,6 +268,7 @@ open class Cpu6502 : BusComponent() {
             }
 
             // no interrupt, fetch next instruction from memory
+            previousOpcodeAddress = currentOpcodeAddress
             currentOpcodeAddress = regPC
             currentOpcode = read(regPC)
             currentInstruction = instructions[currentOpcode]