you need to determine where it is being slow.  some things to think about:

do you connect the client to the web api server via a local network, or internet/wan?  if internet/wan what does your latency look like?

is the database and the web api server in the same local network?

do you have a lot of selects that are occurring?  (either change to a lot fewer selects, use the PS batching, or use local caching)

did you sign your application?  If not, try turning off antivirus.

those are all just guesses.

you need to do performance tuning.  so you need to time your code to see what is slowest and start with that.

Really vogue.  Better to inform us which version of PB, OS you use.  What action makes the slowness?  And where you find the slowness. 

1.  Have you tried finding any function / procedure that's taking long time.
2.  Any script in getfocus / activate event(s)
3.  How you say its slow?  Do you compare with app compiled with previous version(s)?  
4.  Have you checked with HDD?  Recently we faced this issue, once we replaced with new HDD, the issue resolved.

Happiness Always
BKR Sivaprakash

Thank you for the response,

I am using powerbuilder 2022r3, database PostgreSQL and web API runs over the internet.

Below is the server specs and performance from task manager.

internet