"Analysis & Synthesis" takes too long time.

I don't know whether any of these cases still exist, but there used to be special cases where memory inference didn't work or just wasn't supported, resulting in a large logic implementation that took a long time in synthesis. If Analysis & Synthesis did finally finish for you and gave a much larger result than you expected, check whether any of the large blocks of hierarchy should have used more memory and less logic resources.

Try synthesizing each of the top-level blocks separately. (Set the top-level entity in the General category of the Settings dialog box to each of these blocks one at a time.) If any of those takes too long to synthesize, then repeat the process on each block instantiated in that block. If your problem is isolated to one or a few particular blocks of hierarchy, you should be able to find it by synthesizing block by block.