Client freezes

Hello.
I have a problem with a client - it occasionally freezes for like 1 minute. Client doesnt react. When I click during the freeze the screen goes light and I get window "game doesnt respond. -> cancel, disable, wait" I click wait and after around 1 min it works again. Sometimes however freezes for way longer & it ends with a crash. It mainly happens when I open quest log, map, bag or when RDF invite displays. Never noticed it just when walking. Freezes happens often. Like once per 5 mins of playing. Actually sometimes its even 15 mins with no freeze and then a few times in a row.

Now what is weird & what I tried:
- I came on Warmane - Icecrown 2 weeks ago and it happens only here. On my previous server with same wow verstion where I played many years it didnt happen so its not about system probably. Btw my graphics card is 512, RAM 6gb, AMD Radeon 1.50 GHz 4 Core.
- On blackrock realm where I played a few months it sometimes happens too but rarely, almost at all. On Lordaeron happens often too.
- I play on window mode and minimal details anyways.
- Doesnt happen with other games (like skyrim which has higher requirements)
- I removed WTF, errors, logs & cache folders, still nope.
- I disabled all the addons. Way better. After 2h of playing I got like 2 freezes. However its cancer to play with no addons. I use only necessary, basic ones anyways (metahud, DBM, Atlas Loot, epgp, gearscore, gatherer, omen, recount, quartz, power auras, coolline) I remvoed addons and installed same again. Still freezes af.