How to reduce the amount of memory consumed in a C++ application (using SFML)?

Question

C++ / C#

There is an application that uses the SFML library and is written in C++. So far it has almost no logic.
I just sketched sprites there (About 12 pieces. On average, the resolution is ~ 150 px. The largest is 640x480, the background itself covers the entire window). At startup, RAM consumption grows up to 2 gigs almost immediately.
What needs to be done to significantly reduce the use of opera?