Even so, I think there is something else at play here. I'm using a 3GHz Intel i7 with 8GB RAM. With a database of over 5000 players, when I press the "Add Players" button on the Players tab, the dialog opens and takes about 4 seconds to display the list of names. When I search for a player, it also takes about 4 seconds before the search is complete and the list of players updated. 15 seconds is way too long for the that initial delay, although it's *possible* the difference in hardware could account for this (but it seems unlikely to me). 50 seconds to search is clearly too long.
This is probably too much to hope for, but sometimes things like this can be explained by the way the software is being used. For example, recently I received "Out of Memory" error reports from someone. At different times during tournaments, the software would display this error when attempting to use various functions. Turned out the player database had several thousand players (can't remember exactly) and for each tournament every player in the database was added to the tournament first, and then only the players that showed up were bought-in, which was usually 10 to 15 players. So a tournament with 10 players in it actually had, say, 2000 players listed on the Players tab, 1990 of them unnecessarily. The saved tournament files were huge, the application ran slowly, and generating statistics was painfully slow. Removing all those extraneous players changed everything. Any chance you're doing something along those lines?