The fact that you can have tens of thousands of virtual users and just expand an army of load generators to hammer on whatever application you're testing. It seems to be so scalable, and we haven't approached any limits. We have some projects that have over 100 load generators and they don't have many issues using the tool.
Room for Improvement
I think better support for cloud-based load generators would help. For example, integrate with Amazon AWS so you can quickly spin up a load generator in the cloud, use it, spin it down. That way, you're only paying for the actual time that it's being used. I know they have some functionality with that right now, but it could be improved because right now, our projects have to bare the cost of that infrastructure, whether it's an AWS or whether it's their own VMs, so that would help out with that.
Use of Solution
Personally, I've been using LoadRunner or Performance Center for almost 10 years. But our deployed solution, that's available to projects, has only been deployed for about two and a half years.
I think Performance Center is pretty stable. It's the enterprise version of LoadRunner, which was a very mature tool. In fact, a lot of the components or installation files are still the exactly same. They've added this central, enterprise web front end to it that works pretty well. It's compatible on multiple browsers, on ALM. I would say it's a pretty mature, stable product.
Customer Service and Technical Support
More people seem to know how to use Performance Center, so we don't need as much help with it, but it is a more complicated product. HPE, or Micro Focus, has been responsive.
This is complex. We are hosting some of the components in the Deloitte network. The clients or the projects have to set up their own load generators. You have to configure firewall rules. We have to install these agents and point them at our environment to connect and troubleshoot connectivity issues. And every client has a different need. If you're behind a VPN - the app that you're testing - or it's inside the client network, that introduces some challenges. Just by the nature of the tool and what you're doing, it is complex.
It does everything you could hope for in a performance testing solution. It's not cheap, but that's not necessarily a concern for us because we're a large company. But it does anything you can think of. It's a pretty mature, robust tool.
Disclosure: I am a real user, and this review is based on my own experience and opinions.