The super timeline often exceeds 65,000 rows and is extremely slow in
Excel. To fix this, split the file into manageable chunks.

wc -l filename.csv gives the number of lines in a file.

split -l 65000 -d supertimeline.csv supertimeline will generate
multiple files named supertimeline.00 (01, 02, etc) with 65000 lines
each. -l is the line count and -d tells split to use digits for the
prefix instead of letters (00 instead of AA). The second supertimeline
parameter tells split to use supertimeline as the prefex. Omitting the
prefix (supertimeline) and -d will result in files named xaa, xab,
xac, xad, etc.