https://github.com/espeak-ng/espeak-ng/pull/1077

commit 977bff9a061fbd6b44835a6ce45ad887634ae068
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Sun Feb 13 02:54:00 2022 +0100

    event_notify: Remove spurious 50ms delay
    
    event_notify currently introduces an arbitrary 50ms delay between speech
    requests. This is usually unnoticed since it's small. But when
    cancelling a long series of events, they add up to potentially seconds
    of delays, while the user was precisely requesting to just cancel
    everything as fast as possible.
    
    This 50ms delay was probably meant to work around some issues elsewhere.
    If they are still there, they should be fixed, not worked around.

diff --git a/src/libespeak-ng/event.c b/src/libespeak-ng/event.c
index acf3a39e..5561fdbc 100644
--- a/src/libespeak-ng/event.c
+++ b/src/libespeak-ng/event.c
@@ -161,7 +161,6 @@ static void event_notify(espeak_EVENT *event)
 				events[0].type = espeakEVENT_SENTENCE;
 				my_callback(NULL, 0, events);
 				events[0].type = a_new_type;
-				usleep(50000);
 			}
 			my_callback(NULL, 0, events);
 			a_old_uid = event->unique_identifier;
