I'm going to choose a best host for increase speed and performance but I am in doubt with How I can recognize why my site is slow ? is there any way to find out why it is slow I don't want to copy all files in the new host and then understand it is not related to host service is there any program or consol to test the site and understand this things ?
How I can recognize why my site is slow ?
Use Chrome Developer Tools: http://www.chromium.org/devtools
Use top/htop on the server: http://www.howtogeek.com/howto/ubuntu/using-htop-to-monitor-system-processes-on-linux/
is there any program or consol to test the site and understand this things ?
Easy tools - Apache HTTP server benchmarking: http://httpd.apache.org/docs/2.2/programs/ab.html
SIEGE(can use url files): http://www.joedog.org/index/siege-home