Back in the 00s, a story about CPUs getting so hot they'd start on fire went viral. In it was a video of someone removing the cooler while it was running and then a few seconds later a flame appears.

On the one hand, obviously you shouldn't remove your CPU cooler while it was running.

But on the other hand, fans and mounts can fail, so this was still a risk even for people who were smarter than removing the cooler entirely.

It prompted CPU makers to add thermal protections that started out as "if CPU hits threshold, cut power", but over time more sophisticated heat management was integrated with more sophisticated performance and power management.

So these days, if you aren't sufficiently cooling your CPU, it won't die much quicker, instead it will throttle performance to keep heat at safe levels. OP would have gotten better performance out of it after removing that plastic. Assuming it was CPU bottlenecked in the first place. Things like RAM choice and settings can make it a moot point because the RAM can't keep up with the CPU at 100% power anyways.