Your two issues are addressed in
our wiki. See these two pages:
http://www.amule.org/wiki/index.php/AMule_is_slowhttp://www.amule.org/wiki/index.php/AMule_makes_everything_slowPlease read them both. Read them even though I'm about to give you the most likely short explanation.

The reason that aMule causes other internet programs to be slow is that your upload limit is set to 0 (unlimited), or is set too high. So, aMule is saturating your upload bandwidth and other programs can't get a byte in edgewise. The solution is to set a reasonable upload limit somewhat below your line's capacity.
Check how much aMule is able to upload when it is only limited by your line's capacity. This will tell you your line's upload capacity in kilobytes/sec. (Your ISP may describe your line's capacity in kilo
bits/sec. Because a byte equals 8 bits, the kilobits/sec value is 8 times larger than the kilobytes/sec value. The amount aMule is able to use is somewhat lower than that because of communication overhead.) Now, subtract about 10% of that and put the result in aMule's preferences -> Connection -> Bandwidth Limits -> Upload. That will leave enough spare bandwidth for other programs to use. If they are still too slow, you can experiment with lower upload limits.
This will solve at least one of the causes of your slow downloads, too. When uploads are saturating your line, then aMule isn't able to promptly acknowledge data is has received for downloaded files. So, the clients sending that data slow down or even stop sending it.