Diagnosis
Quotient: #vbap of special variants / #vbap of all variants
#vbap of special variants: Number of order item records read forcollective runs in variants which must read order informationin order to check the selection criteria specified.
#vbap of all variants: Number of all order items read in all collectiveruns.
STYLE S_DOCUS1
If you specify values for the fields gross weight, volume, material,plant, storage location or processing time when parametrizing a variantof the collective delivery run (report SAPMV50S), the program must readorder item data from the database in order to locate the correctorders. This requires a lot of time and results in an unnecessarydatabase load if only few delivery item are created. And it does notmake any difference whether only one or several of the fields listedabove have been parametrized. The variants that have not beenparametrized read only order items that are to be delivered - if thedelivery is not cancelled due to other reasons in the subsequentvaluation. If the selection criteria mentioned above are not used,the schedule lines to be delivered can be determined by using an index(table vepvg) and it is not necessary to read the order data.

Procedure
If the ratio is higher than the threshold value, you can use thevariant analysis to find out for which variants mentioned above theratio between delivery items created and order items read is small.Then you can analyze whether they are obsolete or whether they fulfiltheir purpose with other parameters, too.
Further documentation