hello,
if you really want to reindex database, you should follow standard oracle procedure to perform this.
But about slowness with enforce gui, i had same issue for one of my customer and it was due to a change in the way gui is coded betwwen 11.1 and next version. You could try to use a supported version of firefox (depending of your DLp version) or a newer version of IE. This was "magic" for my customer (we have previoulsy tried to reindex database but it didnt change anything).
regards