A very common troubleshooting step is to power cycle your modem and router.
This purges their caches, causes them to re-establish a connection to your ISP, and reinitialises their configuration.
e.g. the device you're using to play Path of Exile
Hardware Acceleration
Preventing web browsers from competing with PoE for your GPU's resources
Processor Power Management
A Windows setting which can sometimes artificially limit your CPU's performance