I don't see why a "click to enlarge" would slow anything down unless you click it
Technically most programs try to anticipate what you will do next and cache the needed information. Caching is a process where you have a limited space of faster moving memory and you fill it with the stuff you think you will need -- or the computer does. In any case, if you guess right you system can get it from that "local" storage and it can be 20 to 100 times faster. In fact, if you had no caching each letter you type might take a full second to show up on the screen. The entire industry is built on predictive logic.
Now each time you do something the system looks in the cache first for the needed data. If it's there, great, if not, then it goes to the main memory area and looks. If you add 1 item to the list of possible things the person can do at a certain point you decrease the amounts of "hits" where the needed information is in the game AND thus increase the amount of time it takes, overall, to retrieve what the systems needs to do whatever you are asking of it. The increase is usually very slight, but over time, it adds up.
Finally, the worst case scenario is when the information is not in the cache and the system then makes room for it by dumping the least used information in the cache so it can put in the data related to what you just requested and that you might, therefore ask for next. Unfortunately, sometimes the data that just got dumped is what you actually request next and the whole thing results in a "miss." Enough misses and the system will flush the cache and start over -- really slowing things down.
The lesson to take away from this is that the fewer options a person has at any given point the higher the hit rate is and the less the system has to go to main memory (there are really several levels of cache but to make things simple I'm using just "the cache" and "main memory"), slowing things down greatly.
I do hope this clarifies things.
AJ