Aion Riftshade

I think all notice that Aion client is incredible slow for 15 years old game, even on top modern computers.
I found that at least some of this freezes is caused by loading of .cal animation files. Single loading can produce 0.5-1 sec freez and multiple (sieges/zergs) can freez client for 10+ seconds.
This .cal files contains list of animations, it is text files with content like this:

// ------------------------------------------------------------------------------------------
// normal state
// ------------------------------------------------------------------------------------------

// ---------- idle animations ----------
nidle_001 = Items\OR_IDF8Lab01a_Nidle_001_loop.caf // prob=0.8
nidle_002 = Items\OR_IDF8Lab01a_Nidle_001_loop.caf // prob=0.2
....

It is not best idea to compile text files in real time and looks like loader is not best optimized and/or bugged.

Yeah, Aion simply isn't optimized for modern systems at all. Add the fact that the game engine only uses 1 CPU core in a time where Quadcores are a minimum spec thing. It's just lagging behind in technology and would require a complete rewrite to fix those things, which NC probably will never do (they pretty much only care for mobile games nowadays due to the way higher revenue with less effort) and GF can't do because they're only the publisher.

At least they optimized RAM usage with 7.5 so that those animations / models / textures stay loaded in your RAM as long as you have enough left over - so it's only 1 lagspike before a big encounter as compared to every time the enemy faction is loaded by your client (pre 7.5). [Recently used over 32GB of RAM after Siege ended (Main client 23 GB, scouting client 11 GB), it's nuts. Those 64GB finally coming in handy I guess.] The most people that had problems with those freezes were on 8 GB on RAM, upgrading to 16 GB fixed most problems besides the initial load for those who upgraded.