clock source and other inquiry

[Last Alternative]

SEE ATTACHED PHOTO

First up, I'm having graphics issues with the spectrum EQ going very slow and choppy and an unreal delay with adjusting the EQ while song is playing, no matter what buffer size I try (2048 and below). No other programs are running in the background. AND I have to keep the buffer size @ 1024 because even 512 is causing occasional high DSP (up to 3 bars) and audio glitches. I have tried all settings and cannot figure out why I can't just run with no problems @ 128 or 256 like everyone else with a good machine (and like my last computers). Somethin aint right.

Here's what I'm working with:
*New iMac 27" (top specs) - got it a few weeks ago
*Apollo twin solo mkII interface
*running 44.1 in Reason & interface console software
*CPU usage set to 80%, also tried none
*clock source set to internal on Reason preferences as well as interface console

I'm sure the graphics and audio issues are connected and I just have a setting wrong or something. My biggest suspect is the clock source but I could be wrong. In the picture it shows Reason's options. The interface clock source options are internal or SPDIF. By default it's set to internal and I haven't tried to change it because I don't know anything about that so I'm hoping you guys can help.

*Keep in mind this is in a song with only 21 tracks and not very many power-hungry RE's/devices. No more than usual. Also this doesn't seem like the same issue I was having before with my last computer because @ 1024 there's no issues recording (zero latency with my interface). Like I said, it just seems like a setting I've got wrong.
Just the other day I did the iMac first aid and also saved the song with the 'save and optimize' option.

So do you think I need to have clock source set to ADAT? SPDIF? I don't even know what that is and the Reason manual doesn't say anything about it.

[MassiveSoundStudios]

I'm not sure what might be causing your laggy graphics, but I can tell you that the clock sources are for slaving your apollo (or other interfaces) to expandable I/O options, like mic pres that have Adat or SPDIF outputs.

[QVprod]

Reason apparently has some CPU issues on Sierra. I believe I saw Joey mention it. That could possibly be what you're dealing with. As stated above ^ it has noting to do with the clock source. It's unavoidable when buying brand new macs, but going forward it's best to stay at least one OS behind the current one. Hopefully that issue will be fixed in the 9.5 update.

[Last Alternative]

OK. Sierra came with my computer. Shocking the Props haven't fixed it yet. It's kinda messing with making music. I just hit them up on FB.
OK thanks dudes.

[fieldframe]

I'm running Sierra with a Steinberg interface and having no problems. My guess is it's a combination of a few things including your audio driver, possibly something weird like UAD having a bug with the Thunderbolt controller in the latest iMacs.

[Last Alternative]

Hmm I don't think it's my interface since there's a graphics issue too. We'll see.

[Biolumin3sc3nt]

I have the same iMac all juiced out, and I'm getting annoying DSP crackles as well, even with 3 bars. What helped a lot is go to your reason app and right click - open in low resolution mode. I know it shouldn't be this way, but it is what it is for the time being. Hope that helps