am I the only one with lag spikes?(DW)

[Higashikata]

Hello,
I am a wow player, deathwing server. I've played wow for 3/4 years and enjoyed the game, till some problems occurred. After my last guild disbanded I litteraly slowed down playing wow. I was enjoying my holidays (when my guild disbaned), but when I came back I realized that lag spike was killing me during raids. So I tried everything, I turned off all the add-ons, I reduced the graphic level, and nothing happened. I tried changing my wireless-pci,to play with lan cable,I tried to change account, still nothing. During this month I changed to win 7 to win 10, the lag is increased (could it be the OS?). So today, I was playing in a raid with my new guild, and It was really frustrating, because I couldn't literally move, I died more than 15 times. Icing on the cake, they called me red ooze at PP and I caused the wipe (well I saw it 30 seconds later). The reason because I am saying it's not my problem, is that in these 3/4 years, I achieved everything, and I never had any type of lag (with ultra graphic and all addons, and the same net line 100/10mbps). To be Honest the lag comes, and then disappear after 2/3 hrs of raids. Indeed my guild had been really patient carrying me till blq, when lags stopped. This problem is that I tried everything in this period, I tried even to write an in-game ticket through the game (with no answers). To be more specifically the lag comes only when I start to raid and rarely when I am doin anything others (i.e. I tried to play bgs, and I hadn't lag). so my question, am I the only one in this server having this issues? can anyone give me some help, since even gms aren't answering?

[Ihazdots]

Try clearing your cache once

[Higashikata]

Try clearing your cache once

I've already done it! Tbh I tried also to change client! the problem persists
Edit: I solved. The in-game GM Octatntis suggested me to try the software WTFast, now the game is a bit slow on loading screen, but the game works fine *-*! thx