Time difference between extraction of encrypted and unencrypted data

Question

Suppose I have two models

class Student(models.Model):
    name = models.CharField(max_length = 60,blank= False,)
    subject = models.CharField(max_length = 60,blank=False)
    marks = models.IntegerField(default =0,blank=True)
    teacher = models.CharField(max_length = 60,blank=False)

and another model

class EncryptedStudent(models.Model):
    name = models.CharField(max_length = 60)
    subject = pgcrypto.EncryptedCharField(blank=False)
    marks = pgcrypto.EncryptedIntegerField(default = 0,blank= True)
    teacher = pgcrypto.EncryptedCharField(blank=False)

Now I want to query on the database. Will there be any time difference? How to evaluate for any time difference?

I am using pgcrypto module . Here is the github link.