System performance reminders - Overheating, slow disk IO, useless network IOs

In the last few months my laptop started to act differently, annoyingly slow, annoyingly hot. I didn't sense changes, reasons for that drop in 'performances'. I was also a bit exhausted so my first reaction was: this one isn't enough, buy a new one. In the back of my mind I knew that didn't make any sense, but still.

Bit by bit issues were resolved. Here's the log:

Browser ad block

I used the usual adblock plus chrome extension. It's subpar and sucked lots of cpu cycle and memory. Recently ublock Origin appeared and requires a lot less resources. Page load 2x faster, memory usage down.

SSD hysteresis

I have an intel 320series 80GB. Configured with auto-trim (fstab under linux). Never cared about trim anymore but when I started to reach less than 1GB free space, speed dropped. Welcome back to the days of mechanical HDDs. Articles say SSD needs free space to allow for wear leveling and such. So i tried to delete the biggest most useless files. Now above 4GB free, still no normal performance. trimming is useless since it's automatic, and sudo fstrim --all --verbose reports '0 bytes trimmed'.

I thought it was a linux bug, removed auto-trim and rebooted. Still nothing. But then manually trimming yeld some output 'xxGB trimmed'. Performance is back to normal levels. Still don't know if it was a bug, where, or if it's expected behavior that  when reaching <1GB free space, you have to force trim ...?

DNS

Installed pdnsd, a DNS cache. For heavy ajax websites like twitter, page rendering was significantly faster. Using twitter made me anxious(see the last point to see why), now I'm mostly zen. (2x, 3x faster perceived speed)

Heatsink / fan

The most recent one. The machine felt hot. But when the system shutdowns for no reason you start to worry. Logs have messages with cpu issued critical warnings about reaching maximum operating temperature -> shutdown. It was often around 80degC, which I thought was alright for CPUs but anyway. Peeking under the keyboard I see no large amount of dust. After a few weeks and 3 more panic shutdowns I tear down the whole thing. Still no big blog of dust that could impede air flow. I use the house vacuum cleaner, fold bits of paper to rub through heatsink fins. Now the cpu tops at 60degC when watching 720p. and below 50 on normal use. What a relief, and a simple fix too, too easy to forget.

I'm tempted to redo it but deeper. I can renew the thermal paste between cpu and sink. And also make new 'fin cleaners' with alcohol to clean the metal surface better.
People told me even a thin layer of dust on metal can change the thermal diffusion power.

On my way I also dismantled the keyboard entirely, it was disgusting. Alcohol bathed keycaps, brushed the board. The laptop feels almost new.

The joy of 'knowing' (a little, I'm still dreaming of fixing mainboards, fans DC motor, firmware and LCD panel)