Learn Farsi: پردازش این انیمیشن زمان‌بر نیست. برعکس، مدل‌سازی آن خیلی سخت است. - Processing this animation is not time-consuming. On the contrary, modeling it is very hard.

Both connect contrasting ideas, but برعکس emphasizes an opposite reality or defies an expectation. Since saying the processing is 'not time-consuming' might make you expect the whole project is easy, برعکس introduces the harsh opposite truth: the modeling is very hard. در مقابل (in contrast) simply places two differing facts side by side.

What does the suffix in زمان‌بر mean?

The suffix ـبر comes from the present stem of the verb بردن (to take or carry). When attached to زمان (time), it creates the compound adjective زمان‌بر, literally meaning 'time-taking' or 'time-consuming.'

How is the word مدل‌سازی formed?

It combines the borrowed English word مدل (model) with ساز, the present stem of ساختن (to make), plus the noun-forming suffix ـی. Together, مدل‌سازی literally means 'model-making,' which is the standard Farsi term for 3D or conceptual modeling.

Could I say مدل‌سازی‌اش instead of مدل‌سازی آن for 'modeling it'?

Yes, you can. مدل‌سازی‌اش (using the attached possessive suffix) is very common and natural in spoken Farsi. Using the independent pronoun آن connected by an ezafe just sounds a bit more formal, which fits nicely with technical vocabulary like پردازش (processing).