I used SocketPunch to install Smash Bros. on my O3DS. It took roughly the same amount of time (give or take two or three minutes) to install it that way as it would installing it from the SD card.
What class is your SD card? Mine's a class 4. AKA slow as hell. Copying a large CIA file to my SD card takes upwards of 10 minutes. I skipped that additional 10 minutes with SocketPunch. It's also worth noting my PC is wired to the router and our router is, iirc, capable of at least 150 Mb/s speeds over WiFi. So in theory, I should be able to send the CIA file across the network to my 3DS for installation at more than 4 MB/s. But, of course, my SD card's max write speed is 4 MB/s.
I could also just be delusional in thinking a faster SD card would improve the install time from SocketPunch to the 3DS. If I was able, I'd happily test it out with differing network and SD card speeds. Unfortunately, I am not able, so I cannot. lol