Your confusing your measurement standards. Bitcomet doesn't
measure speed in kb/s (kilobit per second), it measures in kB/s
(kiloByte per second) This is where your confusion is. Your
speedtest you report is 0.30mb/s or 300kb/s, when converted to
Bytes that is about 37kB/s. Since you report getting speeds of
30kB/s, thats close to your maximum speed your service provides
so there isn't anything you can do without getting a faster
connection.
With a slow connection I'd recommend you disable all the
"services" in bitcomets options, and disable DHT and
peer exchange, as well as longterm seeding.
This will reduce the overhead, and get your speed closer to the
max of 37kB/s. I'd also set your max upload speed to about
30kB/s, this will allow some bandwidth for communications, and
make your downloads run more efficiently.