Tally stores data only on hard disk and large numbers of vouchers also slows down the tally performance .
The numbers of vouchers in your tally can be found by going on tally gateway and enter below mentioned shortcut keys - D + S + S
Splitting the data as per each financial year will improve the tally performance.
Sync data from the required specific year.
Ram - Min 4 GB , We recommend 8GB Working on 64 bit for a operating system.
Processor - Multi core processor, Platinum (OLD) can be upgraded i5/i7 with 4 core for higher data base.
HARD DISK - 7200 + RPM is quite old, SSD for higher data base for better performance.
In Multi-user environment performance of tally might be slow because parent computer is the main system and rest are user or remote desktop for tally.
Avoid deleting vouchers frequently , use cancel option instead
Change deleted voucher sync days to the least from 300 to 15 Days