I'm using PHPStorm since the last year, while I tried WebStorm EAP for the first time this morning; I'm using a Mac with OS X 10.8.2 installed and 8Gb of RAM and I just created a new empty project and wrote some very short TypeScript code on both the IDEs for about an half hour, so I'm not claiming that this is an accurate test; on the contrary, actually it's just an impression.
Does this happen because the PHP plugin or other plugins slows PHPStorm performances ?
Is it normal that I can't keep open both PHPStorm and WebStorm at the same time ? Not that I need this function, it's pure curiosity.
Thank you and best regards
Francesco, the reason why you can't launch PhpStorm and WebStorm at the same time is more historical.
The thing is the both IDEs store their data (settings) in the same folder WebIdeXX. We consider to store this data in the separate folders in the future and have an open ticket in our tracker about this WEB-2569. Feel free to vote for this ticket.
As for the bad performance of PhpStorm could you please collect CPU snapshots for the same actions in PhpStorm and WebStorm and attach them to a new issue? I might be some performance issues with this specific PhpStorm build (126.339).