Here is some general logging info you can enable in your notes.ini. The first entry will log the start of each view rebuild by the updall task so you can calculate the time it took a view by comparing two messages:
; Show some log entries when the updall/update runs
LOG_UPDATE=2
; show the number of transactions
SHOW_PERFORMANCE=1
; Show logfile entries when semaphore waits time out
DEBUG_SHOW_TIMEOUT=1
; Show the thread ids
debug_threadid=1
; And show a semaphore wait log entry after ten seconds waiting.
debug_capture_timeout=10
debug_sem_timeout=10000