Serious junk to check if your 34 is running slow:
A. The no brainers:
IR/RF interference. If your remote is an R-model (rc64R, rc64Rx, rc65R, rc65RX) try RF mode or go back to IR mode.
When's the last time you rebooted? Try that, see how long it takes to go back to being slow.
Are you running hot? Even though you're not getting the temp warnings, your box could be slowly cooking. Check for ventilation.
Got some alignment issues? Remember, pixelating and 771s aren't supposed to be common. Call customer service when you see this stuff.
B. Technical junk
Dish type - If your dish type is set incorrectly, your guide will be slow and randomly miss items. If you don't get 119, then don't be set on a 119 configuration.
Resolutions - Got video delays when you're changing channels? Get audio with "no signal" for a solid 4 seconds? Turn native mode off and set your resolution config to one type and stay there. Avoid 1080p unless you're dead sure your tv will work with it.
Diagnostics/startup codes - Getting harddrive errors? Call customer service to get upgraded to a 44

- or at least something that isn't broken.
C. If problem persists
If all of these things seem to be in good order, you could have a defective unit. Depending on which tech rep you get in customer care, your answers will vary. Sometimes you'll get a replacement, sometimes you will get a service call, sometimes you'll be told it may take up to 10 seconds for some functions to complete. In the end, it depends on the exact situation and the call that the CSR makes. Persistence will probably far if you aren't getting what you need, but make sure you still treat your CSR with dignity and respect.