Giant CPU spikes in loading screens and any time large amounts of monsters appear

Since I posted my issue, I decided to go through the recommended "fix" steps. I ran packcheck and cleared my PoE cache. After doing so, I *seem* to be getting better performance. I'm still hitting shader recompile lag, but I have not gotten any of the serious CPU/shader spikes I was seeing previously. I'm not calling it a success yet. Just reporting findings for anyone else suffering with this issue.

After the fix above, I went ahead and boosted my resolution back up to monitor native 2k instead of trying to run at 1080p as a fix. I also cranked up graphics options I had turned down.