With default settings in with settings that give it more CPU power more CPU cores more RAM more storage etc all of the tasks constantly switch between running and suspended. So it will run for a second then suspend first second then run again and keep doing that. Is this normal because it seems incredibly inefficient. I'm using a Nexus 6

Sounds like throttling kicking in, or CPU usage.

Open BOINC on the device, hamburger (three horizontal stripes), preferences.
Check "Show advanced preferences and controls..." if unchecked.

Scroll to CPU.
What's the "CPU Limit" percentage set to? If 50%, that's the throttling you see, set it to 100%.
What's the "Pause at CPU usage above" set to? If 25% try something higher. 100% disables it.

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I'm actually running into the same issue with my S7. If I set it to 100% it works fine but the battery gets to hot and stops so in the past I've set it to 70% CPU usage so it could charge at a relatively decent pace, stay cool, go fine without being plugged in constantly, and continue to crunch units. I've set it to use all cores, switched between null and 100% for "Pause at CPU usage above" (kind of wish there was a clear cut way to tell it to crunch no matter what), and the rest of the advanced settings are set to default. I also went ahead and set the GUI log level to 5 as suggested previously and not seeing anything out of the ordinary for GUI/Client messages.

I was having the same issues of the client running and then suspending constantly. I adjusted my settings and then rebooted my device and now when I go to open BOINC (it was set to run at startup..not sure why it didn't), it just opens to a BOINC logo splash screen and I can't access any menu items. I'm going to uninstall and reinstall and change one setting at a time to see what breaks it.

You've heard it before, but this time it's really true:
It's not a bug; it's a feature.

It's a bad idea to choose in Preferences to run BOINC 100% of the time, at least for long periods. Although the constant suspending/running cycles would stop, the excessive usage would cause the battery to heat and deplete. Your device's CPU and battery would come to a quicker death.

It's better to set it to something like 40 - 60% most of the time. You can set the temperature limit lower, but then you'd be relying on that one sensor.

Unfortunately, the UI for the Tasks menu in Android is so very awful. All the constant changes to the screen can't help battery life. I tend to switch away from Tasks, to avoid all the flickering of the Running/Suspending. Who thought THAT was a good idea, I wonder...