A common cause of performance issues is allocating too much of the total available RAM to Geneious Prime, and not leaving enough for the operating system to function efficiently. Once the Java Virtual Machine is running the operating system will not be able to access the RAM allocated to Geneious, so if you have allocated too much everything will go much slower. A good general rule of thumb for machines with up to 8GB of RAM is to only allocate half the total RAM to Geneious. For machines with more than 8GB, leave 4GB spare for the operating system.