Hello,
This is the DirectAdmin task queue. It's job is to run every minute and make sure that all the services are running, and to also run commands that are specified in the /usr/local/directadmin/data/task.queue file, if it exists.
Commands include tallying everyone's data every day, restarting services, checking vacation messages to be turned on or off, etc.
I'll assume that the "low speed" you're talking about is a result of the nightly tally. This can take upwards of 30 minutes depending on how many users you have on your server. It's job is to update webalizer and recount all the user usage and limits. If you think this program is running too long, let us know and provide us with details as to what you are seeing.
John