Unfortunately, while the logic of identifying problems by looking at the last installed app makes sense, it fails to take into account the interaction among apps. In other words, it's not the "last installed" app that is causing problems, it is the fact that the addition of that app triggers another app to cause a problem. And even more unfortunately, there's never an end to these potential interaction problems, especially if you have a large number of apps on your phone.
I suspect that many of the reported problems stem from contention for resources among apps, not from faults in individual apps.
In view of that possibility, one of the more useful apps I've found is SystemPanel. It's a task killer, but that's not its most useful feature. Instead, it's useful for identifying overall performance issues through a UI that is significantly better than others.
Here are some things to look for:
() Check the real time cpu cycles graph. If it's pegged near 100% or routinely returns to 100%, your system is close to "thrashing," (i.e. the o/s is working too hard trying to allocate resources among application demands.
() Check amount of available memory. If you're running at 20mg or less, your o/s may be spending time trying to find space for application demands. If you're over 30 mgs, that's not your problem.
() Don't worry about "inactive" apps unless you have very little available memory. They're not consuming cpu cycles. But if you have very little available memory, try killing inactive apps and see if your performance improves. If it does, think about deleting some unneeded apps that take up space.
() Pay attention to the email you're saving. In addition to deleting email, try deleting cache and data from the app's settings. If you're using K-9, "expunge" old email messages you don't want to keep.
() Pay attention to "synching" of your apps. If you have a news reader, for example, stop having it update its feeds every 15 minutes. Update only when you read the feed. It takes only a few seconds to get the latest stories and you won't have the system downloading stories you may never read.
() If you must have real-time notification of lots of things, e.g. messages, facebook updates, twitter updates, news feeds, etc. etc. etc. recognize that such updates will affect the performance of your phone in unpredictable ways. Your system (like your mother) can't do everything at once. If you demand that it show you a YouTube video while it's checking for facebook updates, one or the other app is going to suffer.
() Reboot (power cycle) your phone on a regular basis. I generally do so every morning. Apps may hang; apps may be killed off in an unstable state (if you insist on using a task killer); and s**t accumulates. Give your system a cup of coffee by letting it reboot once in awhile.
