I'm 99% confident that a few years ago the game was down for almost 20 hours while they performed server "hardware" upgrades. At that point, one of several things happened:
- The servers were moved to multiple virtual machines running on one super-computer (ie, 32 processors, 256GB RAM etc) - This is now a common practice with server farms to save space and be more energy efficient. Not to mention it's cheaper.
- The Hardware was actually upgraded to today's standards.
As for the language the server software is programmed in - no one can truly know, but i'd hazard a guess at C. While programming languages have become easier to use and more accessible; the power of their ability to work with numbers isn't that different between 'then and now'. When you compile it, it all ends up as ASM anyway.
I just feel this excuse is a poor one; or as I suggested earlier the current developers were left legacy spaghetti to work with - which isn't optimized and therefor causes artificial strain. More trouble than it is worth to clean up. Who knows.