Performance of ICU 64.2 SimpleDateFormat:: parse(..) on formats that did not have any delimiters between the tokens are significantly slower than the same format with delimiter. Due to this, user performance tests on our product using ICU 64.2 is showing regression.
For example, the performance of ICU 64.2 SimpleDateFormat:: parse(..) method on formats like "uuuuMMdd''T''HHmmss" is much slower compared to that of ICU 61.1.
I have collected the timing data of ICU 64.2 vs ICU 61.1 for SimpleDateFormat:: parse(..) for format "uuuuMMdd''T''HHmmss" using a sample program. Please find the sample program and timing data in comments below..