Hmm - after doing some more experiments - the high load on GPU seems to be pretty much the thing which make the problem visible.
Another interesting thing is - it's usually enough to just 'reload' the very same page in Firefox and the load goes down to ~1% and everything is ok.
Also the kernel perf top doesn't seem to be showing anything interesting.
And a side note - when intel_gpu_top is running - the laptop is actually giving some whistling noise not really pleasant for longterm usage ;)....
Hmm - after doing some more experiments - the high load on GPU seems to be pretty much the thing which make the problem visible.
Another interesting thing is - it's usually enough to just 'reload' the very same page in Firefox and the load goes down to ~1% and everything is ok.
Also the kernel perf top doesn't seem to be showing anything interesting.
And a side note - when intel_gpu_top is running - the laptop is actually giving some whistling noise not really pleasant for longterm usage ;)....