Do you think the program is designed to lose efficiency? lol No. The efficiency is up to the users discretion & skill at using the program. There will always be those difficult to get files that end up needing more sources. Those that are difficult are those from dial up users, those that havent configured their firewalls & nat routers properly, those files that are not popular & thus only few sourcces exist, & of those that only go online for short periods, & all connection types where there isn't much upload bandwidth offered, & or those that have shared upld bandwidth that also share popular files so it's difficult to get an opening in one of their slots for the lesser popular files.
So what can be done about it. Here's some hints: A well set-up LW can start to automatically continue its dwnlding after it's settled down perhaps 2 out of 3 times you open LW.
Optimising LW & Maximising Uplds & Dwnlds A (1st post only) & also
Part B which is even better & last & least are
search & dwnld hints. Sharing more files can help b/c some people filter out those that offer less than 5, 50 or 500 files for example.
I must say sometimes the LW preferences folder can go a bit strange. So deleting it can help (but then need to reset all your LW settings.) Also deleting all your incomplete files from within LW can help but only as a last resort.