Use the tool "Remove Max speed" to search the top speed on the map and remove it (with few points before and after). This can be useful in case the GPS got a mistaken speed.

"Clone" the track if you don't want to lose the original one.

"Clone & Remove Spikes" will duplicate the track and will try to remove various errors produced by the GPS. Try to use it in case the map shows some wrong part of the track, long lines, top speeds, etc.