What's max capacity of Calc 6.2.8 ?

I’ve been using a spreadsheet for 13 yrs to track sales trends. Size is 9252KB. It has 178 sheets in it. It’s slow to load: 1 minute. Afraid if I add more sheets, my document will crash. Suggestions pls. for what I can do to continue yearly trend tracking & avoid spreadsheet sluggishness. Original spreadsheet was .xls and I converted it to .ods in 2017 (I use Windows 10)