Poor performance from excessive garbage collection in the Excel plugin
This problem is related to a third party plugin, and therefore not supported by Atlassian. See Atlassian Supported Plugins for more information.
Confluence is performing poorly. GC logs show constant garbage collection but there is a large amount of memory free.
Versions of Excel Plugin pre 3.6 include a version of JexcelAPI that resulted in repeated explicit garbage collection causing major performance issues.
Upgrade to version 3.6 or later of the Excel Plugin.