Working on Roblox quite a while, the terrain system and the lack of updates they are given is extremely underwhelming.
They feel cheap, sluggish, too janky, and doesn’t at all have any free range for optimization nor adjustability.
Voxels
For Roblox they look decent enough, the major downsides to it are well you can’t really adjust the triangle count. Say you are just making a flat to semi-flat plane of Terrain well then Roblox will just decide to add way too many triangles.
(And you can’t adjust the TRIS count, increase nor decrease)
Water
The default water system provided is very simple. It’s use case is mainly for just showcasing and maybe swimming? Due to the limitations you can’t control the wave directions, make ripples, provide character interactions, have particles built-in for splashing. And the only workarounds for this is to make your own using meshes and are highly unoptimized mostly because LuaU vs C++
Grass
Like the water system, the grass system is diabolically lacking. It features no interactions, not even a change for how the grass patterns should look like. No grass health systems, foliage variations etc. And yes the only way to add more is to just reinvent it using meshes. This is why almost no one who focuses on these systems for their games, use Roblox’s built-in features.
(They are missing out so much on the built-in systems that it could’ve been written in C++ to be way faster than LuaU)
Performance
And just as mentioned above, the performance of the voxels themselves are not at all stable nor optimized for basically any devices. It can still lag players with higher end devices just being determined by how much terrain is displaced throughout a map. Maybe just a suggestion as a feature is to add a controller (siderbar) for triangle count or decimate topology (?) like Blender
This post captures multiple DevForum posts as one big summary, due to the fact that Roblox just never improves especially on their most simple base engine features..
(if they do it’s really rare or takes multiple years to add one feature that many non-roblox games had since the early 2000s)