My Photon once has 250+ apps (after filtering/selecting from 500 apps) and there was only slight decrease in performance comparing now (130 apps) and I hope recent upgraded firmware (198_6 from 154_6) may have more effect than the number of apps, imho... All you need to do is install only apps after thoroughly checking the user comments/star-rating/+1/permissions from AM.. Further you can track the unnecessary apps running in background via GoLaouncher's TaskManager and uninstall it, if it seems like a culprit...
For example, I experienced very laggy performance in my Photon (with 125+ other apps), when I have Amazon-app_store installed (all for that silly 1 paid app FREE everyday offer using fake cc no, etc,,,).. It always runs in BG to check the usage.. After uninstalling that (and its associated FREE paid sw), my Photon was back to the form...
So keep track on bg-running sw and don't use task-killer (it will again and again kill the task which re-appears again and again -- so kills CPU and battery)... Identify the rogue app and just uninstall it...