Hi everyone,
I am also having the same problem, and it seems I have found the solution to fix it.
Well, the closest approach to workaround this problem is by importing the records from .csv file to the table. Please avoid to add row by row from the table edit mode. In addition it will cause the slow access to the page in your wp-admin, it also causes the losing of your new records that you have just added when you save the changes (mostly).
This is the example usage of the large table:
http://www.ikalima.com/reuni/daftar-peserta-acara-hut-emas-dan-reuni-akbar-sma-negeri-5-medan-tahun-2011/
Currently, I have 590 records in that table! Can you imagine it? Before I used the import from file method, I always failed whenever I added some new rows/records into the table or editing the certain records via the table edit mode. But since I used the import from .csv file method, it always succeed to edit my table, especially when adding many records at a time. I even cannot imagine how fast the import process is done! :)
Hope it helps for those of you who are still facing that problem.