Miola, Robert S. Shakespeare and Classical Tragedy:
The Influence of Seneca. Oxford: Clarendon, 1992.

Thesis: Miola's general topic is the influence of the Roman tragedian Seneca on Shakespeare, but he has only one passage which directly concerns Julius Caesar. It occurs in the course of Miola's consideration of Seneca's Stoic philosophy:
The scenes of Brutus and Hamlet, two Shakespearean Stoics, responding to the deaths of their loved ones are revealingly dissimilar. A true Stoic, Brutus appears to give no place to 'accidental evils' (JC IV.iii.146); he bears the sorrow of Portia's death with reserve, remaining scrupulously attentive to his public role and duty. Upon hearing of Ophelia's death, Hamlet leaps forward and wrestles wildly with Laertes, ranting and outbraving the brother in grief. At first glance, Brutus seems to respond with the requisite impassivity and calm. Yet the burden of his grief, we realize, probably accounts for the uncharacteristic anger and petulance in the quarrel scene. As if to underline this possibility, Shakespeare lifts the news of Portia's death from elsewhere in Plutarch, inserting it here in the infamous form of the double revelation. Hamlet, by contrast, loses all composure when he faces Ophelia's death. The emotions that sturdy Brutus represses erupt uncontrollably in the sensitive and theatrical Dane. And the differences here tell much. We wonder at Brutus' remarkable display of self-discipline—courageous, stiff, self-congratulatory, and slightly inhuman. We grieve, however, with Hamlet in his histrionic but human outcry of pain and impotence. Though he has caused much suffering, Hamlet's anguish at the loss of Ophelia is real and pitiable.  (60)
Bottom Line: Sensible.