The CMS has a sophisticated caching mechanism. This caches all possible navigator situations and already computed DML code.

That cache values are stored in memory. That means, depending on the complexity of your navigator logic and how many content you have, the cache may need some memory.

A java servlet in a domino server can take up to 64MB memory as default. So, if the cache needs more memory, you will get a 'java.lang.OutOfMemory?' error on the server console, and the server may crash.

If that's the case, you can lift up the 64MB to any other border with the notes.ini variable

JavaMaxHeapSize?=xyMB

for example

JavaMaxHeapSize?=128MB

The OpenWebCMS? logs memory statistics to the log so that you can check if you're ok with the default 64MB or not.

And if the system is about to run low on memory, it warn you on the domino server console and it will delete the cache automatically, so that memory is being freed up.