macpro wont restart
The startup screen runs after log in but when the bar fills in, it won’t advance to home screen
Safe mode does one pass of Disk repair before it loads, so it can add about five minutes to startup time.
The next Restart after Safe mode, it will rebuild a few system caches, so it will take a little bit longer that usual.
Safe mode loads defaults for everything it can, and loads the minimal set of Apple-only extensions (including NOT loading the display accelerator, which is why screen redraw is quirky and slow). Any changes to preferences you make from Safe Mode will 'stick' in regular mode.
It does not load any non-Apple extensions, so "works in Safe mode" but "not in regular mode" may indicate a conflict with non-Apple extensions.
Only 4GB of RAM for ElCapitan or later is tight. you may be seeing slowness as well as other issues.
If you would like a further analysis, run this little non-invasive Utility to discover more of what is going on inside your Mac:
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