OpenGL FBO performance issue

Question

i'm working on a school project and I've come across an issue with my FBO.

game is rendered in 2 passes: 1) I render to the shadow map texture using an FBO. 2) I render scene normally to the default FBO.

Issue is, for some reason, binding the FBO when i do the first pass slows down my game by roughly 200+ fps, I really don't know what could be wrong with the FBO since it's as barebones as possible. If i were to render the shadow map without binding, so directly to the screen, it'd be 200 fps faster, so it's not an issue of rendering, it's an issue of binding the FBO I believe.

Anyways, here's the first pass function.

//renders to the depth buffer texture.
void firstPass()
{
    static GLuint shadowID = Resources::getInstance().shadowShader;

    shadowBuffer->bindForWriting();//make active frame buffer the shadow buffer
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, shadowBuffer->TEXTURE_WIDTH, shadowBuffer->TEXTURE_HEIGHT);

    //render to the shadow map from the point of view of the sunlight.
    glUseProgram(shadowID);

    ... set some uniforms

    scene->render(shadowID);
    shadowBuffer->unBindForWriting();//set frame buffer to default
    glUseProgram(0);
}

And here is my FBO class in its entirety.

ShadowMapFBO()
{
    init();
}

void bindForWriting()
{
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, FBO);
}

void unBindForWriting()
{
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
}

void bindForReading(GLenum TextureUnit, GLuint texture)
{
    glActiveTexture(TextureUnit);
    glBindTexture(GL_TEXTURE_2D, texture);
}

void BindTexture(GLuint textureID, GLuint location)
{
    glUniform1i(textureID, location);
}

void unBindForReading()
{
    glBindTexture(GL_TEXTURE_2D, 0);
}

GLuint shadowTexture;

int TEXTURE_WIDTH = 2048;
int TEXTURE_HEIGHT = 2048;


GLuint FBO;

void init()
{
    glGenFramebuffers(1, &FBO);
    glBindFramebuffer(GL_FRAMEBUFFER, FBO);

    shadowTexture = Util::createTexture(TEXTURE_WIDTH, TEXTURE_HEIGHT, true);

    glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, shadowTexture, 0);

    glDrawBuffer(GL_NONE);
    glReadBuffer(GL_NONE);


    GLenum Status = glCheckFramebufferStatus(GL_FRAMEBUFFER);

    if (Status != GL_FRAMEBUFFER_COMPLETE)
        printf("FB error, status: 0x%x\n", Status);
    else
        printf("Shadow Buffer created successfully.\n");

    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

Here's how I create my depth buffer texture.

static GLuint createTexture(int width, int height)
    {
        GLuint textureId;
        glGenTextures(1, &textureId);
        glBindTexture(GL_TEXTURE_2D, textureId);


        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, width, height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

        int i;
        i = glGetError();
        if (i != 0)
        {
            std::cout << "Error happened while loading the texture: " << i << std::endl;
        }
        glBindTexture(GL_TEXTURE_2D, 0);
        return textureId;
    }