Check your preset manager. You may really have too many gradients already.
As per with brushes. Have your gradients in sets, the names of which will appear in the list when you click on the drop down in the Gradients panel. If you have to many, then start with a reset, and replace or append only the set(s) you need at any one time.
Why couldn't you save them?
And that would mean that you have about 10k gradients loaded!