Small speed up joining large remote rooms (#9825)

There are a couple of points in `persist_events` where we are doing a
query per event in series, which we can replace.

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/9825.misc b/changelog.d/9825.misc
new file mode 100644
index 0000000000..42f3f15619
--- /dev/null
+++ b/changelog.d/9825.misc
@@ -0,0 +1 @@
+Small speed up for joining large remote rooms.