Running an online service is a massive undertaking, especially when you consider something of the size of Office 365. Not only do you need to keep adding new capabilities to the service, but you need to balance this with maintaining the lowest possible Cost of Goods Sold (COGS) and ensuring the service is efficient and performant.
The Project engineering team have been hard at work over the last few months performance changes across the service including the Project Center, Creating and Publishing a project, Submitting a timesheet as well as general tweaks etc. over all the tiers of the service. I’m sure we’ll see some of the benefits of this when the next on premises edition of Project Server comes out and we dig around
The Project team posted over at blogs.office.com about these changes and a few more including increased limits for the number of projects in a PWA site (5000 up from 2000) and the number of PWA instances available to be added to a Project Online tenant (7 up from 3).