Yes, there are many iphone user who face the problem of camera running very slow, the camera shutter opens slow for most of them and you are not the only one. When an iPhone user launch the camera app on iphone they keep waiting for couple of next seconds and only after 6-7 seconds it opens up, it may go to 10 or more seconds time for some iphone users before the camera app actually ready to snap a photo or do a video recording.
There are numerous ways to make camera app runs faster on iphone, if your iphone is jailbroken then you have more options to improve the camera app speed on iphone.
With Cydia Tweaks
Snappy is one such cydia tweak which lets you launch iphone camera from almost any app which you are running on your iphone, by just tapping the status bar or else you can use activator to decide how to quick launch camera on iphone with this cydia tweak, read the guide here for more info.
Another quick way to launch the camera directly can be done by just sliding the lock screen upwards which will open the camera, this can be done by installing a cydia tweak called Camera Grabber, you can read about here for more info.
With Third Party Camera Apps
Another option of making the camera work faster and more responsive, is to install some third party apps like Quick Camera Video [$0.99] or some others apps which lets you just tap on screen to take a photo quickly, read here for more info on this.
Trick To Open Camera Shutter Faster
The last and the simplest way to make iphone camera shutter opens up faster after launching it can be done by launching the camera from the lock screen in iOS but double press of home button which shows the little camera icon and then tap on it, it will launch the camera more faster then one in which you tap on camera app icon on homescreen.