Canvas Draw 6 runs very slowly on my mid 2016 MacBook Pro. Changing the contrast on a page-sized 300 dpi raster image (& only one file open) takes about 30 seconds. The same image in Canvas Draw 5 is completed in 1-2 seconds. Larger files take forever. I have uninstalled Canvas Draw 6 & reinstalled it. I reinstalled Canvas Draw 5 to make sure it ran as fast as I thought and it did. I have an LG UltraFine Display. If I make the same contrast change without the external monitor attached, it takes about 10 seconds in Canvas Draw 6, but less than one second in Canvas Draw 5. I uninstalled Canvas Draw 5 before installing Canvas Draw 6.
Canvas Draw 6 does everything much slower than Canvas Draw 5, such as selection, scrolling or keyboard commands.
I've encountered variety of problems with v6, to the point that I will not use it. I have both versions installed and I'm doing fine with v5 on a new Mac Mini with Mojave 10.14.6.
Also reverted to v5, because of icon and preview issue.
I received some suggestions from CanvasGFX & tried them, but they didn't help. Perhaps the next round of suggestions will be more helpful. In the meantime, since I spend so much time working with Canvas Draw, often in large documents, I have uninstalled CD6 & I'm using version 5 (& still very thankful to have Canvas Draw).
I have a mid-2016 MacBook Pro with 16 GB RAM & a 2 TB solid state drive. Usually I use it with a an LG Ultrafine (27-inch (5120 x 2880) display, but sometimes with a lower resolution 27" Apple display or just with the MBP's 15" display. No matter which display I use, the speed differences between CD5 & CD6 remain.
I upgraded to OS 10.15 Catalina last night. The old problems I had with CD6 didn't go away, but I had no new problems running CD5 or CD6, and no CD crashes or ETs.
I never install a new version of the system, I wait for the .1 iteration. There's always some bugs in the first one. I'm hoping a new version of Canvas Draw will be released soon, there are some things in V6 I like, but too many bugs to use it for now.