Distortion after playing a loop region for a while

Hello, I am working on a project and in order to test some track adjustment I selected a region of about 10 seconds and activate the loop play. It plays correctly for around 4 to 7 times (it varies) and then it started to distort and the RT CPU meter goes beyond 120%. FX CPU meter is low (around 20%). Reaper shows the transport bar current position information in red and starts to sluggish. If I play stop and then play again the problem is gone until some repetitions are played. I checked disabling the effects (ReaQ and some Waves FX) with no luck. I am on a windows 10 machine with Reaper 5.12 on a portable installation. My interface is a M-Audio ProjectMix I/O which is also a surface controller. Any ideas about what could be happening?

Are you connecting via usb or firewire? If firewire, I had a similar issue and I had no luck with a few FW interfaces - turns out it was my TI FW chipset on my motherboard - settled for usb and all works fine.

My interface/controler is Firewire only.... The thing is that this happened in just one project so far since I am using Reaper, 2 months more or less.

If it is just one project, when loading it, bypass all vsts and bring each vst online, one at a time, and test after each one.