latency

version: 2.1.2
computer: Dell laptop E6530 i5 processor
operating: Windows 7 pro 64 bit
DAI: Yamaha Audiogram 6 USB
Disc drive is less than half full

I have several songs that have 31 and 45 tracks respectively and are each about 3 min. long. Starting about month ago I experienced latency when recording additions/changes to this two songs, but have never experience latency before that. Is there a point where if you have a a lot of tracks that things slow down? If so what is the limit?

As projects get bigger it puts more demands on the computer system.
There is no absolute limit to the number of tracks - it depends on the computer, the sound card, what else is running, and many other factors.

Optimizing a computer for best audio performance is a big topic, but there are some tips in this article: http://wiki.audacityteam.org/wiki/Managing_Computer_Resources_and_Drivers