If you suspect LW is taxing on your system & that's the reason for your problem, here's some hints:

As far as reducing processes, there are processes that run that really aren't needed. I came across this http://www.windowsstartup.com/wso/browse.php?l=0 some time back. I've come across other sites that discussed this also but didn't make a note of them.

Ways to reduce LW's taxing on cpu: most recent Java; set all uploads & downlds to autoclear; close all LW windows you're not using at that time via the View>Show/Hide menu, eg: monitor window, etc.; disable Ultrapeer capabilities under Speed setting; reduce upld speed to about 70-80%; reduce upload slots to something practical; reduce downld speed to 80-90%; don't use the Resume button to continue all your incomplete files ... this will definitely tax LW, your cpu, & possibly your connection quality; don't downld too many files simultaneously; leave LW to settle before using - perhaps 20 - 30 mins.; share less files.

That's some ideas off-hand. The more incomplete files you have & the more shared files then the longer it takes for LW to settle down.

Some people breathe some fresh life into LW via deleting all incomplete files that are 0% for example. After opening they click on the very top of the Progress bar so that all files are arranged by % downlded. Then scroll down to & select 1st with 0% & then scroll down to last with 0% holding SHIFT key select it so all those at 0% are selected. Then press the Stop button. Then go to incomplete folder & arrange it by size & delete all those at 0 KB. This can apparently speed up opening LW & give it a bit more energy so to speak.