ya..I agree eConnect has been tested for heavy loads.But In 100+ records definately it will take som more time (doc per entry point ) compared all of them in singly entry point.
Generally,"Serialization" and "entry point" will consume the time in econnect.In 100+ times of serialization definately take more time .It may be take speed in server but in client it will take more time.
I have geneated POPEnterMatchInvoice schema .It takes 45 sec per document,I also processed 1023 records in same time in single entery point .
Before processing I will take all validations and skip the error possible records.May be error occured we can seen in error log which contail the all in formation about the error record.