Hi
Swaps are not critical, it is just a data that has been pushed out of the SAP cache as it is getting full, or is running out of free entries.
The data could still be read from RDBMS, it might also be in the RDBMS cache.
The significance of the number of swaps will depend, at first on the uptime of the system (from what I know swaps counter in ST02 are only reset when the instance is stopped), the longer your system is up, the more swaps you could get.
The amount of available memory is another key criteria, if you system is short in memory it can be impossible to avoid swap.
The system usage can also have a big impact, if you've got a lot of users, working on very various sets of data (different SAP modules, countries, companies...) it can be difficult to avoid swaps.
1918603 - High swaps in transaction ST02
Regards