just came to say i was also experiencing this except on opera gx (which is chromium based i believe?)
it was driving me insane i thought it was my gpu that needed to update or lack of memory until i just reset my browser's profile and started from clean, checking each extension
and lo and behold it was malwarebytes browser guard extension
i couldn't load image heavy websites (like amazon for instance) and if it loaded it would take forever otherwise it'd pretty much render my browser frozen until i task manager killed it
not sure if i got the debug logs before i tried ceckelberry's suggestion of factory resetting the extensions (which worked) but i'll upload my logs as well just in case!
BG-Logs_v2.6.0_2023-04-23_14837.txt