The encryption bit depth can impact performance as system load increases. The tradeoff between performance and security can lead to a preference for 1024 bit keys over 2048. If thread affinity to processor cores does not induce a performance penalty then increasing the key strength to 2048 seems most appropriate. Otherwise “throw more hardware at it” becomes the loudest mantra in the organizations that I have developed software for and supported in production.
According to the NIST, that was one of the reasons Rijndael was chosen during the AES selection process over Twofish. It was faster in hardware implementations. These days, hardware acceleration can encrypt data streams at pretty insane speeds. These days cpu is cheap enough that even software implementations can do some decent throughput. Personally, I think all traffic on the internet should be encrypted, including email. It would stop a lot of casual snooping. Of course, this won't happen because the real snoops (the governement) would be inhibited as well.