The R2 Group Chat client defaults to a very verbose logging level. While logging enabled as a default can be helpful when first rolling the solution out and catching unexpected errors, it doesn't help when it impacts the client performance. 

As the result of a customer visit with this issue, a member of their own team found some settings they thought would be acceptable and after double checking the best supported configuration is as follows, notice the highlighted parts 

<log4mgc>
   <file value="%userprofile%\tracing\GroupChatConsole.log" />
   <maximumFileSize value="1" />
   <!-- in MB, 2047 max-->
   <maxSizeRollBackups value="1" />
   <filemode value="truncate" />
   <level value="FATAL" /> 
</log4mgc>

TomL GCKid