Clean your heatsink out, and also consider replacing the heatsink paste: that CPU is so old, its entirely possible a cheap thermal pad is no longer usable (commonly used on laptops and stock desktop HSFs).
I'm going to guess your problem is not CPU related, but rather a hardware issue relating to other hardware that Firefox uses (GPU, audio, …) Firefox spends most of its time idling in event loops; it's not a batch job like a compiler.
Note that I'm not blaming ffx, just witnessing something weird and wondering if it's due to using rust parallelism in ways not done through the usual cpp libs.
Very doubtful. The only thing I could think of that might conceivably cause similar symptoms would be AVX2, but none of our shipping Rust code uses that.
Odd then. I wasn't even using a specific webpage, just loading the previous session (~20tabs of average intensiveness). Chromium has the same kind of session and it never causes similar heat spikes. Anyway I'll try to reproduce it even though it's not pleasing to overheat like that.
