I've recorded eleventy jillion guitar tracks and never had a problem like this.  I'm sure it's just some stupid thing I've forgotten or I'm not thinking of...but even though I've got my Audient iD4 set at low latency and 128 samples I'm still getting very serious latency delay when trying to record a guitar track in a current project.  Have both record and input monitoring engaged so I can hear GR5 or Amp4, etc...tone but the delay is too long to record with.  My short term solution was to just the record the part dry and then effect later.  But that's not a real solution at all.  Anybody have a guess what I'm forgetting or not doing??
 
Geeze Louise.
 

Hi. Perhaps you're using a plugin that uses look ahead functionality. LP plugins?
Which plugins do you have in the project?
All the best.

I've hit that wall a few times myself. I tend to try and strip out anything non essential untill all tracking is complete. I've gone so far as to render a rough mix and send all tracks into archive just to relieve processing chores.

Zargg
Hi. Perhaps you're using a plugin that uses look ahead functionality. LP plugins?
Which plugins do you have in the project?
All the best.

Probably this. I never have the issue unless using the Cakewalk LP plugins.

I'll 3rd that. I always forget to bypass them and bingo. Midi is even worse. 
 
128 is a reasonable buffer but what counts is what Sonar is reporting to you in preferences as your Total Roundtrip Latency. Example mine shows as 20 ms which is enough to throw me off. I've never had a system that could work with Guitar Sims as the lowest RTL I can get is around 12ms but then everything grinds to a halt. 

Sometimes I have plugins on a bus or master that I forget about. Voxengo Curve Eq has got me a few times.

musicroom
Sometimes I have plugins on a bus or master that I forget about. Voxengo Curve Eq has got me a few times.

Yep - some of these plugins -and- to the reported latency, because you're using PDC (plugin delay compensation).

Try disabling plugins until the latency gets better.

(Reaper actually reports this for individual plugins - so when I'm set for 64 samples latency, some plugins drive it up to 128)

huh...I never record with the input monitor(echo thru) engaged.  That always causes a delay for me.  My soundcard has a mix app that I can direct monitor with...So the guitarist can always hear the clean gtr in at least with no delay  and the effect is a little delayed.  Not sure if I'm helping the situation here.    

Click the PDC button on while tracking. This takes care of (I don't know how) plugs in the master that have large delay.

I always hit the FX bypass button when recording guitar. Especially if it's a large project and I don't have time to go through everything and check for delay causing plugins. If you need effects on your guitar as you record, you can always temporarily engage just those effects after enabling FX bypass.