RED native footage speed ramps

Hi,
I wondered if anyone else was getting strange behavior trying to do speed ramps/changes on native RED footage. I have a project with using native RED 4k (and 5k) in multi-cam clips. There are four angles, and multi-cam seems to work as expected. The project itself is in a 1080p timeline because we're finishing 1080p, but there are multiple instances where we zoom into the image. We're trying to cut natively. What we really want to avoid is having to optimize the footage, because there's just not enough room on the san for that at the moment. The footage is connected to shared storage through fibre channel.

We're running into problems whenever we do speed ramps and changes, which would result in beach-balling. I expect that the machine has a harder time because it's not ProRes, but would it really just choke and not ever recover? Does anyone else have trouble with speed changes on native RED footage? I would have thought this would be widely known since this is such a common configuration.

The machine is a new-ish 27 iMac with the 4GB 780M video, 3 TB fusion drive, 16 GB Ram. Is it a RAM issue? Otherwise, the timeline plays fine and only gets choppy here and there. We're not using a Red Rocket or any other thing like that.

I have experience issues when applying certain effects to R3D footage in FCPX but nothing what you just explained.

I could give it a try when I hit the shop and report back.

I find it best to transcode and playback in proxy mode with Red footage, online at the end with native.

I edit a lot of RED footage and un-rendered playback of native clips are usually choppy on clips that have any effects, frame transformations, especially multi-cam and speed changes.