We do not perform the titration while the sample is at its original temperature because reaction is too slow at original temperature and requires high activation energy.
A titration is a method where the concentration of an unknown solution is ascertained by comparing it to a solution of known concentration. The analyte (the unknown solution) is typically added in a known amount to the titrant (the known solution) from a buret until the reaction is finished.
The slow energy step in the reaction process may require a high activation energy, and the proportion of activated molecules needed to reach this reaction at room temperature ororiginal temperature is too low, so most molecules cannot cross this peak. As a result, the reaction at room temperature proceeds very slowly (the final product is not reached). Heat can enhance the proportion of active molecules and catalyse a larger-scale reaction.