I need some advice about Midi timing

Have you tried bypassing effect (E key) while tracking? Some plug-ins have "look ahead" on them that will insert latency on you by default. You can bypass effects to record, then turn them back on afterwards.
 
You can also manually offset latency, but if that is not consistent, it may not help as much as you would like.

Just to clarify, It's not that the FX are so CPU-intensive, but that they use look-ahead processing with an internal buffer that adds to the audio latency. So getting a faster computer won't help except to the extent that it allows you to lower your ASIO buffer to reduce the total latency. But plugins that need PDC may use buffers that are significantly larger than your ASIO buffer so the net improvement may be marginal.
 
SONAR applies plugin Delay Compensation (PDC) to other tracks so that they'll play in sync with tracks/buses using plugins that require it. So all tracks in the project are affected by the added delay of plugins on other tracks. Aside from bypassing all FX in the project, another option is to enable PDC Override (Shift+E or click the PDC button in the Mix module) which disables PDC on input-monitored audio tracks (including soft synths) so you can rehearse/record without latency. This works so long as the plugin requiring PDC isn't on the track your monitoring.
 
Ultimately, though, you want to try to avoid using plugins that require PDC during the tracking phase of a project.