Where are you seeing performance issues? As your issue might be less with your CPU and more with storage or some other bottleneck.
The console is laggish. I have just setup a Windows 2022 server 2 CPUs with 2 cores and 32GB of RAM
I've used the diskspd utility to do some benchmarks
-t4 - o32 -b4k -r4k -d120 -Sh -D -L -c5G
I've done tests by incrementing the -w parameter by 25 starting at 0
The results are as follow w0 CPU AVG 92.66% TOTAL READ IO/S 11649.49 AVG LAT 10.97
w25 CPU AVG 3.26% TOTAL READ IO/S 214.61 AVG LAT 425.091 WRITE IO/S 71.72 AVG LAT 522.129
w50 CPU AVG 37.05% TOTAL READ IO/S 130.02 AVG LAT 447.86 WRITE IO/S 130.29 AVG LAT 541.224
w75 CPU AVG 3.54% TOTAL READ IO./S 116.64 AVG LAT 248.616 WRITE IO/S 347.08 AVG LAT 285.8
w100 CPU AVG 33.62% WRITE IO/S 152.35 AVG LAT 838.956
The proxmox host has 2 ST600MM006 HDD (10K RPM) configured in Raid0 with a PercH710
Which do you think you need more? High core count or higher clock speed, or balance of both?
Those cpus are more than fine for anything you'd might throw at them. That said - if you get an upgrade for cheap, why not? But nothing I'd say it might be worth hundreds of dollars for forced upgrades.