When Tor changes circuit it only changes middle node and exit node, the entry node stays the same since the Tor started, so I guess the entry node is limiting the traffic if you make too much traffic, right? So changing the entry node is the idea for speeding up the Tor, I don't want to restart it to change the node that may cost too much time on connecting to the network, anybody has anyway?
To actually answer your question, since nobody did that until now:
- shutdown Tor
- restart Tor
In case you use TorBrowser on Windows the path is
...\Tor Browser\Browser\TorBrowser\Data\Tor\state. You can just kill tor.exe via Task Manager, delete the file, switch back to Tor Browser and have TB automatically restart Tor via the popup that tells you tor is no longer running.
so I guess the entry node is limiting the traffic if you make too much traffic, right?
The long guard rotation period is for security reasons. The more often you pick a new guard, the higher the chances that you will encounter a bad one (i.e. owned/controlled by the party you want to hide from).
There is one other way you can change entry node when you start Tor browser without changing any of the setup. What you may do is to start the Tor browser roughly about a minute before you connect to internet. What happens is Tor browser try to connect but because there is no internet connection it can not connect. Tor browser then assume that guard is down and pick a new guard. Thus you have a new guard and completely new circuit now.