Confusing latency issues

What FX do you have on the guitar tracks? Do your guitar tracks go through any folders or get sent elsewhere? Have you also got FX on your master? some FX introduce latency, so check to see where your guitar signal is going. You can check the latency when you go into the FX for a track/folder/master and clicking on each effect. It shows you the latency in samples down the bottom of the window.

I've never seem input lag myself either from CPU stressing, which is why I suggested it might be latency inducing plugins. What Reaper FX are you using on the guitars? What interface are you using? what buffer sizes? what do your latency figures say up in the top right hand corner of the reaper window? Chuck up the project file so we can have a look at it (no audio files needed), and see if we can see anything wrong/replicate the problem.

Freeze your tracks and see if that helps. Also check in the performance manager window and see what plug is using what in the way of memory and cpu

Oh my word. I've never felt stupider in my entire life..... Ok. Just delete this thread after you're done laughing your backsides off. I accidentally knocked the power cable out of my laptop so it was running on power saver. Of course this means my performance settings were set to Sloth Mode.. I need to sit in the corner for a bit and think about what I've done.

Ha, sweet. easy fix then. We've all done it.