By default Malt runs in high quality settings on the viewport. As a result, many low-end PC hardware cannot handle it and become unresponsive. To solve this, there are few settings in the Properties window > scene tab > Malt Properties you can lower.
Here is our recommendation for low-end hardware.
Line Width Max: lower this, but impact is minimal from default. Higher number (more than 10) will cause huge performance impact.
Sample Grid Size Preview: must not be lowered to zero or one, huge speed improvement. This is like the number of samples in Cycles/EEVEE. note that unlike EEVEE and Cycles, this value is squared. So, for example, 4 means 4x4 samples, 16 in total.
Shadow Cascade Distribution Exponent: must not be lowered too small or the shadow will get blocky, minor impact. This is the equivalent of the Distribution value in EEVEE for Cascaded Shadow Maps. It controls how shadow resolution is distributed along the view distance.
Shadow map resolution: Just like in Eevee, lowering this will improve speed at the cost of quality.
Transparency Layers: Major speed up when lowered. This determines how many transparent objects can overlap, like the Max Transparency bounces in Cycles. It only affects the camera view, transparent shadowmaps always use a single layer since they fall back on dithering.
Here are the formulas for the 3 types of shadow maps available in Malt
VRAM impact (less is better)
High impact: (resolution^2)*8
8 cascading maps
Medium impact: (resolution^2)*6
Cubemap with 6 sides
low impact: resolution^2
Just a single map
All 3 types of shadow maps are created when you change to render preview. Even if you only use Point lamp shadow map, the other 2 shadow maps will exist in VRAM. To get the best performance, lower the other 2 to something small, like 64 or 128 resolution.