Performance of Fetching News
If this is the wrong forum, I apologize.
I have just started using Calibre (I am three days into it) and am particularly impressed with the automatic news fetching capability. I do have some comments on the performance of this and how to improve it.
First, I run Calibre on a Mac and the target device is a Kindle so that is what these suggestions apply to. Also, I decided to email the results to my kindle.com email address.
To see how the news feature worked and which feeds I wanted, I turned on about 50 of the built-in feeds, told Calibre to fetch them all and ran with all default settings. On my older dual-core iMac this ran for hours.
Looking into this, I found two thing to speed this up.
1) In preferences, in the advanced area under miscellaneous set:
"Maximum number of waiting processes" to 6 (or more if you have more than 2 cores). Also, uncheck the box that says "Limit the max. simultaneous jobs to the available CPU cores". (Note: I also tried setting this to 4 and to 8. 4 left about half of one core idle. 6 kept both cores busy with very little idle time. 8 also kept both cores busy but seemed to take a little longer to process all the feeds. The machine was idle except for Calibre during this.) My tentative rule of thumb for maximizing processing performance is to set this to: #cores*2+2
2) Under tweaks, under advanced in preferences change
"# The number of seconds to wait before sending emails
public_smtp_relay_delay = 301" from 301 to 0.
The delay is to prevent some email servers from rejecting the mail from Calibre as spam. This does not seem to be a problem with the amazon kindle email. The first run I did took 4 additional hours to complete because Calibre was waiting 5 minutes between sending each email.
With both these changes the wall clock time for fetching all the feeds, converting them and emailing them to the kindle went from about 6 hours to one hour.
Anyway, I really like Calibre and hope this helps someone. Please fell free to correct me if I have anything incorrect or unclear.