I talked to you last night about battery autonomy after performing a evasi0n7 jailbreak, and today it's time to talk about the performance of the terminals after using this software. Considering that iPhone 5S or iPad Air you can't run anything in particular Mobile Substrate, I will tell you my experience with the tablet iPad 3, which did not have the best performances in iOS 7. After performing jailbreakand the installation of some tweak- users who use Activator or a somewhat functional Mobile Substrate, can say that the performance of the tablet was not affected in any way.
In general, performance will not be affected if you have the latest iDevices with enough RAM and a dual-core processor, but of course everything depends on the number of tweaks installed/used simultaneously. If you use tweak-s like SBSettings, or tweaks that implement real multitasking in our iDevices, then there are quite high chances that iOS will run quite hard. iPhone 5S, iPad Air and iPad Mini with Retina Display will run the best whatever kind of tweaks are available in Cydia, but in general it is advisable not to install a lot of packages in order to benefit from performances as good as those obtained without jailbreak.
In case you're wondering, simply doing one jailbreak Your iDevice should not suffer performance without plugins installed.
