vimrc affects startup time, but like any program it isn't the lines but the work done which will make it slow or fast. How slowly does your computer read a 1000-line text file? vim is fast, setting some parameters in vimrc doesn't change that. Avoiding configuration that will make your life easier out of fears about performance is premature optimization.
If you have a ton of autocmds for frequent events, things can slow down. I also find that things can get slow when LOTS of calls are made to a language other than Vimscript.
But fundamentally, run Eclipse and Netbeans and gedit and emacs - vim should compare favorably even with a ton of config.
If you want to actually profile your startup time, try this on a recent version of vim:
vim --startuptime=vim.log
If you have a ton of autocmds for frequent events, things can slow down. I also find that things can get slow when LOTS of calls are made to a language other than Vimscript.
But fundamentally, run Eclipse and Netbeans and gedit and emacs - vim should compare favorably even with a ton of config.
If you want to actually profile your startup time, try this on a recent version of vim: vim --startuptime=vim.log