How to make faster first search at Unity-Dash? Way slower than second one

After a reboot, the first search using Unity Dash will be slower (15 sec) than the second search (seems instant), on my system at least. I guess this is because file index is cleared after a reboot and recreated as soon as first Unity Dash search is done.

If this is the case, auto-recreating index at system start-up should work. I could imagine for example automatically running some command at the system startup for gathering info before it is requested by user via Unity search.

I'm interested particularly in searching for programs.

I have disabled online search for better performance while no interest in that.

My current machine configuration:

Ubuntu 14.04.1 x64 on HP 655
Processor: AMD E2-1800 APU (2x 1700 MHz)
Graphics: Radeon HD 7340 driven by xOrg "Gallium 0.4 on AMD PALM"
Memory: 4 GB (real 3.6 GB)
HDD: ATA Hitachi HTS54505 

Theoretical benchmarks: CPU, HDD. I will benchmark those myself eventually...

Following topics may help you:-

• Question about indexing and search may be found from :- How does Unity's dash index and search work?
• Speed up for searching programs, visit How to speed up search for locally installed applications in Ubuntu 13.10's Unity Dash?
• Also have a look at How to speed up the Dash response? :- Compiz Config tweak may help.

I know that this is not exact answer of your question as quoted:-

I guess this is because file index is cleared after a reboot and recreated as soon as first Unity Dash search is done.

Is still unanswered and requires more attention.

In case you're only interested in the Dash to start application, you can simply uninstall lenses with sudo apt-get remove --purge unity-lens-[lensName]. As advised by BullfrogBlues here, that most likely means removing all of them except for unity-lens-applications and possibly unity-lens-files.

In case you like the Ubuntu system but feel like Unity is getting more and more crowded with functionalities you don't use, you can also consider moving to some other Ubuntu flavor. On my side I am now pretty happy with Ubuntu Gnome and a customized Cairo-dock!