Checkpoint Duration - HDR - Sync/Async

Hi everybody, my environment : Two identical servers running AIX 4.3.3 - IDS 7.3.1 UD1 running HDR between both database servers DRINTERVAL : 360 segs (=> ASYNCHRONOUS)I have only one production database on Buffered Logging Mode. I implemented HDR in order to protect the data changed after the last backup, and to be able to execute reports/DSS-querys on the secondary server (in that order). I read that the checkpoint between primary and secondary servers running HDR are synchronous, regardless of DRINTERVAL parameter is -1 (=> SYNCHRONOUS) or not. When i execute a very heavy dss query on my secondary server, it affects the performance on this server and i have noticed that it affects the duration of the checkpoint on both servers (even getting 6 times the normal duration). It is logic if i consider that the checkpoints between primary and secondary servers are synchronous, am i right ? or am i missing something else that could be affecting the checkpoints duration on both servers? Is it possible to minimize the impact on the primary server's checkpoint duration ? For examble by tunning some parameters like DRINTERVAL, CKPTINTVL(240 segs. on my servers), or the difference between these values (I am just guessing). Or the Logging mode on my only production database. Thanks in advance Regards sending to informix-list