Although I personally didn't feel a major difference in speed, apparently there IS a major increase of read and write time when using LAZ. Once again the lidR doc is an excellent source of information on the topic (in this vignette):
We can therefore speed-up the computation time by a factor of 2 by using the las format instead of laz. Obviously the gain is less significant for more computationally demanding processes.
So for faster computation users can opt for las files instead of laz files. Obviously, there are good reasons to use laz files instead of las files. The strong compression brought by the laz format has a lot of advantages for storing data. It is up to the user to choose a format by considering the trade-offs between space and computation time.
In actual computational tests (
chm <- rasterize_canopy(ctg, 1, p2r())) further below in the vignette, they demonstrate a factor x4 between las and laz.
It also elaborates a bit on las-indexes (.lax), which apparently can have a similar impact on computation time (factor x2 at the cost of one-time processing time to create the index and the negligible storage space for the .lax file [>0.1% of the point cloud storage space in my experience]).
So for me personally, I conclude that
- for distribution and archive, .laz should always be the format of choice. LAStools laszip offers a quick way to compress.
- data, that is often and actively processed, quickly justifies storing the decompressed .las files for significantly faster computation
- LAS-indexes (.lax) are always a good idea (little addition of storage for significant boost of computation time), as soon as you process your data more than once and of course only if your processing tools support them (lidR and lastools do, for PDAL I don't know).