In some cases, I see different behavior when I switch on and off the “Enable OpenCL technology to speed up…. In the Hardware Acceleration tab of the preferences.
However, irrespective of this setting I see the spinning balloon and also a preview of the effect selected. Don’t you?
This is indeed not a preview of the effect applied to the clip. I don’t know any way of previewing the effect on the clip. What I consider a faster way to getting a better preview of the effect rather than apply it to the whole clip (and the hassle of removing it again) is to drag the effect to the FX line under the track in the timeline. It can simply be removed from there too.
Now as of version 19 there is no FX track anymore. You have to manually insert it, by selecting Add Tracks from a menu that opens when you right click in the timeline.