My iPhone 4 is literally a trainwreck

So I have had this iPhone for about a year and ten months now. I am eligible for an upgrade but I figured I would just wait until the 5s comes out (only a few months...). Then... it was like the apocalypse hit my phone. Here is the list of problems:

-Lock button broken
-Home button works about 1/20 times, so sometimes I have to wait for somebody to text me so that I can even unlock the phone
-It constantly LAGS and apps are like a ticking time-bomb and crash all the time
-It even struggles to pull down the notification center
-Camera takes about 30 seconds to open...

Is this normal? I know software outdates the hardware, but I'm not playing crisis on this thing. It can't even load Facebook most of the time. I have over a gig of free memory (is that enough?) left on it, so if that was an issue I have that covered.

This just bothers me because the phone was completely capable just 8 months ago. I have been taking great care of it and cosmetically it's in fantastic shape (aside from the broken buttons, but those weren't my fault).

Overall I just don't know what to do. Do I stick with this molasses speed plagued time wasting machine a few more months, or do I just get an iPhone 5 now? Is there anything I can do to speed this baby up and get it back to its glory days?

Thanks for the responses ahead of time!