Try a low latency kernel on your desktop if you use Linux, that should improve responsiveness some more. Apparently the increase in power consumption is minimal - I use (K)Ubuntu's low-latency kernel even on laptops these days.
I'm actually not sure why it has the effect it does, entirely, because at least in terms of raw resource use the browser doesn't seem to be eating that much stuff, but the effect in practice has been well beyond what can be explained by perceptual placebo. (Maybe there's too many things competing to get the processor at the VBlank interval or something? Numerically, long before the CPUs are at 100% they act contended, even in my rather simple setup here.)
Or, to perhaps put it another way, Linux already has this sort of prioritization built in, and it works (though it's obviously not identical since we don't have split cores like that), but it seems underutilized. It's split into at least two parts, the CPU nice and the IO nice. CPU nice-ing can happen somewhat automatically with some heuristics on a process over time, but doing some management of ionice can help too, and in my experience, ionice is very effective. You can do something like a full-text index on the "idle" nice level and the rest of the system acts like it's hardly even happening, even on a spinning-rust hard drive (which is pretty impressive).
This, automatically turning on battery optimizations when an internal battery is detected, and automatically applying a 'small speaker' EQ to internal speakers are a few changes that would make Linux feel so much better on a laptop.
EDIT: I searched a bit and, although I haven't found instructions anywhere, I did find people saying that the low-latency kernel decreases throughput as a tradeoff to lower latency. Have you found this to be the case?
Also, another source says that the preempt kernel might be better for some workloads: https://itectec.com/ubuntu/ubuntu-choose-a-low-latency-kerne...
Can anyone comment on these?
In general terms, one either just installs the specifically recompiled package (-preempt, -lowlatency etc.), or recompiles their own. The related parameters can't be enabled, because they're chosen as kernel configuration, and compiled in.
I'd take such changes with a big grain of salt, because they're very much subject to perceptive bias.
I think most people just don't care or don't know that they care about responsiveness.
Turns out that the cost of NUMA balancing (https://www.kernel.org/doc/Documentation/sysctl/kernel.txt) was outweighing any benefit we might get from it. The problem is that NUMA balancing is implemented by periodically unmapping pages, triggering a page fault if the page is accessed later. This lets the kernel move the page to the NUMA node that is accessing the memory. The page fault is not free, however; it has a measurable cost, and happens even for processes that have never migrated to another core. The lowlatency kernel turns off NUMA balancing by default.
Instead of switching to the lowlatency kernel, we set `kernel.numa_balancing = 0` in `sysctl.conf` and accepted the consequences.