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In LW, go tools > options > advanced > performance. Disable DHT, Ultrapeer capabilities & TLS > Apply > ok. Restart LW & see whether your connection reaches turbo again.

Do downloads start ok & then go to 'awaiting sources' or do some downloads show 'need more sources' straight away? If the file's host goes offline, then you'll see the awaiting sources message. Try going back to the search page, right click on the file you're downloading > search more > get more results. Sometimes that can get the download going again.

Files that go straight to needing sources & never start downloading are usually fakes. Check the threads below for more info.
Fake files showing up in search results

And also some general info here (for video as well as music)...
How to find music

Virus thread: Typical virus spam file sizes - Make a note of them (click on blue link to see)