How to speed up installing plugins and upgrading WordPress

As you’re using a VPS with SSH access, give WP-CLI a try http://wp-cli.org/

can work wonderfully http://centminmod.com/nginx_configure_wordpress_ffpc_plugin.html#installwp

for example to install limit login attempts plugin just run this command from SSH within your wordpress install directory

wp plugin install limit-login-attempts --activate --allow-root

full list of command line options at http://wp-cli.org/commands/

updating plugins http://wp-cli.org/commands/plugin/ & http://wp-cli.org/commands/plugin/update/

wp plugin update limit-login-attempts --allow-root