It looks different from any purslane I have seen with the leaves like that. Mutant?
The thread "Purslane: the Weed variety" in
Purslane and Portulaca forum
This is spurge.
But your's doesn't look like that.
Do you have a reliable nursery who can ID it?
I would at first glace think it is purslane too. Are all the leaves pointed? The stalk is the main reason I wonder also.