How to get this LSM9DS1 code run faster?

Read the forum guidelines to see how to properly post code and some hints on how to get the most from this forum.
Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in code tags.

The code as posted is very hard to follow without any indenting. It is also hard to copy to a text editor or the IDE. Properly posting code is important if you want help.

Which Arduino board?