What is ShotSlow in Touhou 7 : Perfect Cherry Blossom ver 1.00b?

I found out recently that in Options --> KeyConfig of Touhou 7: Perfect Cherry Blossom, there is an option called ShotSlow. It turns out that I have it turned on and I wonder what does this option really do and if I should turn it off.
I saw people writing that it makes game easier and should be turned off if you are not casual player. But, if I try to fly any character through the screen, shooting or not, I don't really see any difference - if I wasn't told that character should slow down on firing, I would say there is no speed difference.
Description says "Move slower when holding down shot key", but I don't really see any difference. Is the difference in speed very small, hardly noticeable for new players? Or maybe, for some reason, it doesn't work for me?
Best Answer
On the touhou wiki (http://en.touhouwiki.net/wiki/Config), I found an information about the shotslow :
In the game options screen, there is a "Slow Mode" (Shotslow?) option. It causes the game to slow down when there are lots of bullets on the screen. This invalidates replays and high scores.
Also, the french version of that page (http://touhou.net/wiki/Configuration) adds something interesting : you can still unlock good endings and extra stages with this option.
Pictures about "What is ShotSlow in Touhou 7 : Perfect Cherry Blossom ver 1.00b?"



How do you slow down in Touhou?
Normally, you can move more slowly and precisely by pressing and holding the "Slow" button (the Shift key on keyboard). Turning on ShotSlow will make you automatically move more slowly when you shoot.How do you unlock Touhou 7 extra stage?
Unlocking Extra To unlock the Extra stage for a specific character and type, you must reach the "Normal Ending" (finish the game on any difficulty without continuing) with that same character and type.How many levels are there in Touhou 7?
Perfect Cherry Blossom consists of six regular stages with four levels of difficulty, and also offers a practice mode, allowing the player to play through a single stage at any time, provided they have completed it already.Who is the final boss of Touhou 7?
The boss of the Final Stage, Yuyuko is the Master of Hakugyokurou. She is the true mastermind behind the ongoing winter and seeks to take the spring that the player has gathered.Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Brett Sayles, Evie Shaffer, Anna Urlapova, Karam Alani