Looking for freeware lib for memory compression/decompression

I'm developing an app that reads in a relatively large text file (12 megs) before it can get started. Now I use a single raw read and do some parsing.

I'd like to reduce the load/launch time and thought I could shave some time by handling the file as compressed. I was hoping to get some guidance as to an easy to use freeware library (preferrably open source) that does speedy decompression. My thinking was to read it in, then do in-memory decompression. Also, I would want to be able to compress perhaps 5000 bytes to put in the registry as binary data. Some password protection or encription would be a plus, but not essential.

I'm getting ready to look at 7-up and ChilKat, but I thought I'd ask first before staring at them. I'm appreciate hearing from people with experience with either/both of the above, or a preferred alternative.

TIA