<configuration>
<options>
...
<databaseBlockCacheMiB>0</databaseBlockCacheMiB>
</options>
</configuration>
Use your desired value instead of 0 (zero being auto detect). The old default was 8 MiB. The new, as of 0.11.4, goes up to 64 MiB for machines with enough RAM. So probably you already have a more reasonable value without needing to tweak.