Dear Sai,
No matter, how many tasks you have in the database, as only tasks that are displayed are taken in to account.
There shouldn't be any serious delay in response when 50 users share the database simultaneously. At least we can say there is no delay when 30 users share the database.
If you have any questions or problems don't hesitate to ask me.
Best regards,
Victoria Vinnichuk <support@vip-qualitysoft.com>
Sales and Customer Service Manager