Try to decrease max_notes if CPU limit reached

Experimental

source_microdexed.h

@@ -29,6 +29,13 @@ class AudioSourceMicroDexed : public AudioStream, public Dexed {
             getSamples(AUDIO_BLOCK_SAMPLES, lblock->data);
             if (render_time > audio_block_time_us) // everything greater 2.9ms is a buffer underrun!
               xrun++;
+            if (render_time > audio_block_time_us - (audio_block_time_us / 10)) {
+	              Serial.println("At CPU Limit");	
+                uint8_t nnotes = getNumNotesPlaying();
+                //setMaxNotes(nnotes);	
+                max_notes = nnotes;
+	          } 
+
             if (render_time > render_time_max)
               render_time_max = render_time;