Yes, this is a confirmed vanilla problem with the keyhole song, but this was caught during moderation of a couple of songs on SMWCentral that were reported as causing SFX lag. Basically, heavy CPU usage on the music can caused missed ticks on the SFX side for the same reason why there was slowdown on the music side for the longest time, as the SFX side was never updated to incorporate the forced tick mechanic that was used for the music.
Yes, this is a confirmed vanilla problem with the keyhole song, but this was caught during moderation of a couple of songs on SMWCentral that were reported as causing SFX lag. Basically, heavy CPU usage on the music can caused missed ticks on the SFX side for the same reason why there was slowdown on the music side for the longest time, as the SFX side was never updated to incorporate the forced tick mechanic that was used for the music.