I have huge project, workspace is near 1.5 gb
Is there any way to disable raster layers generation, to speed up map creation and decrease db size? I use only vector.

The raster has to be generated as it is required for the contour and isobath generation, and the raster itself is not stored in the DB. The raster data is cached to disk, so that the flat raster and shaded relief layers can be regenerated more quickly if required (e.g. palette or SR settings change), but it does not increase the size of the DB. Some tips to reduce project build time would be to limit project areas, increase contour interval and to limit the range in which minor contours are created.

Does interpolation and smoothing affects build time?

Interpolation not at all, smoothing only very, very little. Contours and isobaths take the most time, and size of project is the biggest factor. If you can split your project, and perhaps also your workspaces, that would help the most.

Thanks!
One more question, about splitting.
What will be faster:
1. Large rectangle, build and export
2. Split this rectangle for example on 4 small. Build all 4 projects, and combine on export
And will we get visual artefacts in 2-nd case, on boundaries?

Probably no. 2, but you would have to confirm this for your particular case. You may see the edges to some extent, but if you align the boundaries exactly (enter the GPS coords, rather than use the marquee tool), then these artifacts should be kept to a minimum.