Uniform latency on all sound cards and live sets?

[Garbled Lingo]

I have been using live for about a year now on my macbook pro(4G RAM, 3.06GHz Intel Core 2 Duo) with no latency issues......but recently i have been experiencing a uniform latency on any of my live sets, including my dj template, that have any significant amount of tracks or devices running. Starting a new track from the ground seems to work fine, no latency there......but when i open any of my songs that are very far along (more tracks, effects, plug ins etc.) there is a latency that i can't remove by tweaking any of the latency settings in Live's preferences. This happens no matter what sound card i am running, i have tried several including a couple MOTUs, an alesis usb, and the macbook's built in sound card. I am not savvy enough in the computer game to localize the problem, and since the problem seems to have developed just recently, or maybe over time slowly and unnoticed, i am worried that my computer may have developed a hardware malfunction of some kind. I am wondering what are any steps i can take to rectify the problem, or what can I do to find out what is causing this latency? Is there anything i need to adjust on my computer itself? Is my computer failing? Any knowledge would be appreciated and reciprocated with warm vibrations and best regards:)