To find players quickly in the Available Players Table use your browser search function, which is activated by typing "Ctrl + f".
If the Available Player Table seems to be running slowly, close the browser search function when switching the position filter.
Also, if you have Auto-Team Stack or Exclude Opposing Defense on when you are excluding or locking players, the Optimizer does a lot of recalculation after each change you make to see which players can still be inserted in a lineup. To exclude and lock players faster, shut off Auto-Team Stacking and Exclude Opposing Defense until you have several players selected and there is the possibility some players can't be used because of salary or team stacking requirements. This will help it run faster.