How can i optimize my schema to avoid creating multiple expressions?

[#1]

Hi,

Attached document contains link table schema where Table1 and Table2 are linked based on two fields which have many to one relationship. Requirement is to compare one trend line(cust) with other lines as where it falls in the range. To achieve this we ended up using multiple expressions for each customer, due to which the object has become heavy ending-up in performance related issues. Please suggest a different way of achieving this. Thanks.