Oneconnect profile resolves the issue with routing but it breaks some other functionality with the application itself so we would rather not use it.what is broken? have you tried oneconnect with 32 bit mask (i.e. 255.255.255.255)?
sol5911: Managing connection reuse using OneConnect source mask
http://support.f5.com/kb/en-us/solutions/public/5000/900/sol5911.html
what can I do to optimize the iRule performance?i think class command could have better performance comparing with switch glob. you may enable timing and see how many cpu cycle irule utilizes.
class wiki
https://devcentral.f5.com/wiki/iRules.class.ashx
iRules Optimization 101 - 05 - Evaluating iRule Performance by Deb Allen
https://devcentral.f5.com/tech-tips/articles/irules-optimization-101-05-evaluating-irule-performance.Ufh8nW0-ZQI