Performance issue with SQL regexp_like?

I have a rather complex SQL statement using regexp_like that is basically
searching for a field in a source file.



Omitting all of the other stuff above and below.



The regexp_like is (Please ignore any typos. The source is on a machine
that I can't reach with the laptop with this email account)



left join source on Regexp_like(srcdta,
'[^A-Za-z0-9_@#$]'||trim(field)||'[^A-Za-z0-9_@#$]','i')



When I try to run it via interactive SQL., it runs for about 5 minutes.



I tried changing it to this to see if the performance was any better.



left join source on srcdta like '%'||trim(field)||'%'



This version returns in seconds. That is a huge difference!!!
Unfortunately, it finds lines that contain the value but may not be what I
am after. For example, if I am searching for ACCT, this also finds ACCT01.



Is there an issue with regexp_like? Should I use the second method and then
add a regexp in the RPG code to filter out the ACCT01 lines?



Any ideas where I go to from here? Please do not suggest packages like
Hawkeye. This is a client's machine and we can't add packages to their
machine so it has to remain native code.