For a customer we want to upgrade to Mendix 4 from Mendix 3.3.2. I read that by upgrading from Mendix 2 to Mendix 3 the system uses less memory. But how is the memory consumption between Mendix 3.3.2 and Mendix 4. - In case no optimization changes will be done in the model I expect it will increase, because now objects will be created in memory and kept in memory before transferred to database. But on the other hand it could be less when the activities can be handled more fast and give the memory free. The reason for this question is, that the current system is running on his maximum of memory. And we don't want take the risk that after upgrading the system cannot be used and in that case we need first to upgrade memory before upgrade Mendix model. But if experience shows that the memory consumption will be less, then we have another point to migrate to the new version.
Jacco van de Put
The general answer is: it depends on your application.
But, generally speaking, we've noticed that most apps consume more memory in 4.x than in 3.x. You can easily check this by converting and running in your test environment.