Measure slowing down my rapport

Hey

So i have a measure set up to assign a letter to each supplier based on how mutch we buy from them.

It is to categorise theire importance.

The measure i am currently using looks like this:

Lev kat. PBI = SWITCH(
TRUE();
[LCC] = 1; "A";  <---- This measure is there to keep it as an A if the calculations equals 1
[Bare K2] = 1; "K";  <---- This measure is there to keep it as an K if the calculations equals 1
SUM(Ark4[Sum of total sales]) > 10000000; "S";   
SUM(Ark4[Sum of total sales]) > 3000000; "A";
SUM(Ark4[Sum of total sales]) < 300000; "C";
SUM(Ark4[Sum of total sales]) > 300000; "B")

Now this is then put into a matrix with a list of all supplier names and numbers.

The rapport is insanly slow, so i am hoping for a better surgestion so it can be sped up.

Thank you in advance

- Robin