So, I completely uninstalled EN (incl Legacy) using CleanMyMac X, ran a 'smart scan' with CleanMyMac X to make sure there were not any left over niggly files. Re-Booted my Laptop, then re-download EN from the website. Fingers crossed, it seems to be running Ok now - have been running it for 4 days with no hic-ups. All notes displaying correctly and quickly. The only problem now is that I cannot right click to save files to EN as I got rid of Legacy, but I email the files to myself and that seems to be just as efficient anyway, but this feature is not available in Basic (and a separate issue to this thread).
I will repost an update if I run into any further problems, but for now, seems Ok.