I'm tempted to say that as 4.1 is out of service, you are VERY exposed to a failure stopping your application altogether...but you know that anyway!
On the supported CICS TS 1.3 & 2.2, the Web support has improved considerably, and so you might well get a resolution of your performance problems by simply upgrading.
You do not say where the delay is being generated. If it's because of insufficient network capacity, then no help from CICS I'm afraid.
If the delay seems to be CICS related, then you are going to look at what exactly your application is doing to generate the Web Pages. Obvious things to think about are moving any Web Pages into Programs and then Data Spaces.
If the source data is in VSAM files, then move them into DataSpaces, or use CTS 2.2 whereby locking contention is reduced. Alternatively,think about the relationshiop between VSAM CIs and the clustering of keys. You might have too few LSR buffers for the activivty.
A quick fix muight be to install a cloaned AOR and then use the MVS TCP/IP Port Sharing function to do load balencing between them. This might well alleviate the performance problem entirely - but it depends on your CICS Application, the source of the data and any affinities present.
All in all, you need to investigate WHERE the delay is occuring before anyone can suggest anything further.
This was first published in March 2003