Thats not the case for sure, however you could be right that there could be some delay because of it.
You can check it for yourself by monitoring ram rclone is usingm chabe bellow the acdcrypt: to match your mount ( so the proper pid may be grabbed if you are using multiple rclone mounts and/or copy/move/sync something at the same time
rclone=$(pgrep -f acdcrypt:)
while > /dev/null
ps --pid $rclone -o %cpu,%mem,cmd
Not set your buffer to 1GB eg something you know it wont be filled instantly with your connection and you will see that movie will start playing way before buffer is filled. On my server in average i need around 4 to 5 minutes to copy 10G and I tested playout with 10G buffer and out of 5 tries the playout speed was exactly the same as with buffer set to 0 ( default is 16M )