General

Very weird Cpu usage issue

So, I've tested this a bunch throughout the past few days and came to no solution.
Whenever I enter an instance (like Gollux or a boss run), a few minutes after entering I experience huge CPU usage. It spikes from 11 or so to [b]90-100%[/b] of my CPU usage. It creates unbearable lag between the game and my computer in general.

My computer can play Maple with no issues, when it comes to hardware. My internet connection isn't amazing but it's more than enough for GMS, I live in NYC so I'm not very far.
(Intel i5 Processor 2320 3.0GHz, ASrock z75 pro3 mobo, 14gb ram, AMD Radeon HD 7700 Series GPU, etc.)

I've checked my GPU and CPU temps before and while I'm playing the game. It's ranged at 35c-45c.

It apparently happens on both GMS and MapleSEA. I can't figure out what the actual cause is, but the game is unplayable. Has anyone else experienced this or has advice?

P.S: I'll add that this is only recent, and I built a new computer about half a week ago. I think it only started after that, but I have no issues with other games at all. Only Maple.