Your Time Capsule has that "lag" because the drives spin down (goes to sleep) if there has been no activity for a certain amount of time.
This is also the reason that it gets disconnected after a certain amount of time. The drives go to sleep for two reasons: one, it's to save power; there's no point in spinning drives that aren't being used, and two it's to maximize the life of the drive.
I wouldn't recommend this method for sharing and/or storing files as the TC was meant for backups. If you need storage for your files I would definitely recommend a NAS like the Synology or an external Thunderbolt drive. I personally use the Synology with my Mac and have no problems whatsoever.
"Hack" to Keep the Drives Spinning
Since the drives spin down when there is no activity for a given amount of time, a quick and easy hack would be to access the drive for some minor operation to create activity. A simple bash script would work perfectly:
# Script to create activity on time capsule to prevent drives going to sleep
# It creates an empty text file named tempfile.txt then removes it
touch /Volumes/<Time Capsule Volume Name/tempfile.txt
rm /Volumes/<Time Capsule Volume Name/tempfile.txt
Save that bash script as
keepalive.sh or something that makes sense to you in a easily accessible location like a "Scripts" subdirectory in your Documents folder. Make sure it has the "executable" attribute by issuing the command
chmod +x keepalive.sh.
crontab you can easily set this script to run every X mins, hours, days, etc.
crontab for editing by issuing the command
add the following line to your
*/15 * * * * /bin/bash /Users/<username>/Documents/Scripts/keepalive.sh
The time is set for every 15 minutes. If the lag is still present, you will need to adjust that value to something smaller. Just use
crontab -e to edit.
NOTE: most likely your "editor" environment variable defaults to
vi (default). It's not difficult to use, but it's definitely not intuitive for new users. Use nano instead by invoking the
crontab editor with this command (pay attention to case):
env EDITOR=nano crontab -e
You will then be able to use Ctrl"Key" combinations (i.e. Ctrl"S" for "Save"). The commands will be at the bottom of the screen.