Web 8.5 object caching does not help services performance at all

Question

We have installed Web 8 and have object caching configured on both Discovery and Content service. We have also set the defaultStorageId to defaultDb and set cache equal to true. We have setup a logger for caching to make sure cache lists are being created and to confirm there are no errors about memory size or other things.

However, when I load my CD webpage with all that caching enabled I get the same performance from the Web services as I do when all the caching is disabled. The performance is not good and enabling caching does not help it looks like. Any ideas?

FYI. When I enabled longlived cached on the CD web app performance is great. The page loads in < 500 ms, but when I disable the CD web app cache it takes 10 seconds to load because it has to talk to the Content and Discovery service.

Thoughts?

...
    <ObjectCache Enabled="true">
        <Policy Class="com.tridion.cache.LRUPolicy" Type="LRU">
            <Param Name="MemSize" Value="512mb"/>
        </Policy>
        <Features>
            <Feature Class="com.tridion.cache.DependencyTracker" Type="DependencyTracker"/>
        </Features>
        <RemoteSynchronization FlushCacheDuringDisconnectInterval="20000" Queuesize="512" ServiceMonitorInterval="10000">
            <Connector Class="com.tridion.cache.RMICacheChannelConnector" Host="...." Port="1099"/>
        </RemoteSynchronization>
    </ObjectCache>
    <Storages>
        <Storage Class="com.tridion.storage.persistence.JPADAOFactory" Id="defaultdb" Type="persistence" dialect="MSSQL">
            <Pool CheckoutTimeout="120" IdleTimeout="120" MonitorInterval="60" Size="10" Type="jdbc"/>
                <DataSource Class="com.microsoft.sqlserver.jdbc.SQLServerDataSource">
                    ...
                </DataSource>
            </Storage>
        </Storages>
</Global>
<ItemTypes cached="true" defaultStorageId="defaultdb"/>
...

I can't remove the comment at this point but as noted below I also tried excluding the taxonomy but that did not change anything.

<ItemTypes cached="true" defaultStorageId="defaultdb">
  <Item cached="false" storageId="defaultdb" itemType="Taxonomy" />
</ItemTypes/>

Also in regards to other comments:

1- I removed the FlushCacheDuringDisconnectInterval and ServiceMonitorInterval nodes so they would take on their default value but no change.

Answer 1

Here is the link to the docs for JVM Heap size settings, as per Vikas' suggestion in the comments above: https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v1/GUID-882178AA-A7E5-451B-8CD3-9F06D967F9BE

Make sure it is 512 MB, as suggested. The default Java setting is something like 64 MB, so if the Tridion install script didn't override it with 512 for some reason, then this could do it.

For reference, here is the Oracle documentation for further settings that can be made: https://docs.oracle.com/cd/E15523_01/web.1111/e13814/jvm_tuning.htm#PERFM161