Second when sending my emails the entire website get much slower.
Last but not least I find some functionality awkward to use, not really intuitive or user friendly. Fortunately the documentation is okay, but a good extension should not require a documentation, especially when it is as simple as sending emails.
This extension still needs some work, I am disappointed. Hope to see some improvement, especially on the performance aspect.
Reading your review and the 220 others, I feel like you tested an other component... are you really talking about AcyMailing?
The only reason the send process could be slow is that you selected the option to embed your images in the Newsletter.
So instead of a path attached to your website, the picture itself will be included in the e-mail and may slow down the process (if you send 1Mo picture to each user, it will obviously take some time...).
So you can simply turn off this option (which is not enabled by default by the way) and you will see the real speed of AcyMailing! ;)
We love receiving feedbacks, it helps a lot to move forward.
So we would really appreciate if you could send us an e-mail about the "functionality awkward to use".