In ITMS 8.7.3 and earlier, the MaxConcurrentPackageInfoRequests core setting is set to a hard limit of 100 concurrent requests.
You want to utilize your SMP Server CPU resources to a higher use value.
ITMS 8.7.3 and older
Starting from version ITMS 8.8, the maximum value has been increased to 500.
Note that setting the high number of threads for this request type may negatively impact performance such as high CPU on the SMP server or Wait Locks in SQL database.