OS: Win10 16299 x64
RAM: 16GB DDR3 1600 (dual channel)
CPU: Intel Core i7 4700MQ

My Bitcoin data dir is stored on my 5400rpm HDD. The OS is installed on 128GB SSD.
Though HDDs are expected to be slow, bitcoin-qt seems to be much more slower than my expectation.

Today, I was restarting bitcoin-qt full node on my PC, it showed that my node was 520 blocks behind the network. During the syncing process, taskmgr showed that HDD active time is 100%, but, the speed was EXTREMELY slow: validating one block seemed to take about one minute!

dbcache size was already set to 2048MB, which was not seemed to work.

Then, I tried some tricks to "boost" the syncing process:
1.Use procexp to suspend bitcoin-qt.exe;
2.Execute following command in cmd:
3.Wait for the command to complete (took me about 5min).
After that, my taskmgr showed that the "cached" RAM size increased significantly.
4.Use procexp to resume bitcoin-qt.exe;

Dramatic things then happened: bitcoin-qt was significantly "boosted up". Time consumed by validating each block has shrunk to only several seconds!

I wonder if I made any mistakes? Doing such "manual optimization" is so strange...