If you're still running the game from a HDD upgrading to an SSD is relatively cheap and painless. But, if for one reason or another that's not an option for you I've discovered something that might help.
Recently I noticed it was taking longer to load into maps than it had in the past, and that an issue with lag spikes/stutters when enemies were spotted that I had previously fixed had returned. While troubleshooting I checked Windows defrag, confirmed that I had a defrag scheduled weekly and that it was reporting 0% fragmented. On a whim I ran Auslogics Disk Defrag, which reported 36% fragmentation!
Obviously that needed to be fixed, but rather than a basic defrag I used ADD's optimization functionality (which still defrags, you just have various optimizations available to make while the defrag runs) to make sure WoT was loading as fast as my hardware allowed. (Other defrag programs might not have this, but there's a free version of Auslogics Disk Defrag if you need it.) Basically I used ADD's optimization to move the WoT folder to the start of the disk, where read speeds are the best. To do this, I configured the Optimize by Disk Zone profile -> Fast Zone, checked User Defined Files and added the Wot folder and saved it. Then, back in the main program, instead of just clicking Defrag I clicked the dropdown on the Defrag button and selected Optimize by Disk Zone.
This took a while, longer than a basic defrag, but I just let it run over night and it was done by morning. Before this I was loading into maps with just a couple seconds to spare, and sometimes a couple seconds late. After the optimization I'm loading into maps 20-25 seconds before the match starts, so that's a very noticeable improvement! The lag spike/stutter isn't 100% fixed, but it has markedly improved, going from a solid second or two lag spike when enemies are spotted to a split second stutter. Still have some troubleshooting to do there it seems.
Anyway, the moral of the story is: Don't trust the Windows built-in defrag, use a 3rd party tool. Hope this helps!
Source: https://www.reddit.com/r/WorldofTanks/comments/em1var/performance_tip_for_hdd_plebs_use_a_3rd_party/