Firstly, ditch SpeedFan. It's always been inaccurate on every system I've used it on. Use something like HWMonitor (I see that you say you double-checked and it gave the same readings...so why not stick with the better application
Secondly, what are your laptop's specs (brand/model preferably)?
Thirdly, the CPU is definitely going to ramp up when doing compression as that's a very CPU-heavy operation. Are the fans in your laptop good? It's possible that the cooling in your laptop is just bad and not up to par with doing a lot of heavy operations.
+1 to Donetao's suggestion of repasting your heatsink in your laptop if you can. That should at least help somewhat, and you'll be able to clean out any dust buildup that you couldn't get to when cleaning out your vents before.
Would also suggest that you look into getting a laptop cooling pad with a good enough fan to cool your laptop down.
Development takes a lot of CPU (believe me) - developing on a lower-end system or one with terrible cooling is difficult. My gaming laptop makes a much better development machine than a couple other systems I had in college because it keeps cooler, has more memory (extremely important), and more powerful CPU to compile/build faster.