Whisk olive oil, Pecorino, and 1 tablespoon lemon juice in a medium bowl to blend. Season with salt, pepper, and more lemon juice, if desired. Set dressing aside.
If using fresh fava beans, cook in a large saucepan of boiling salted water until tender, about 4 minutes. Using a slotted spoon, transfer to a colander set in a bowl of ice water (do not cook frozen beans). Drain and peel; place in a large bowl.
Return water in saucepan to a boil; add asparagus and cook until just tender, about 4 minutes. Using tongs, transfer to colander in ice water.
If using fresh peas, return water in saucepan to a boil; add peas and cook until tender, about 3 minutes (do not cook frozen peas). Drain; transfer to colander in ice water. Drain vegetables. Add to bowl with fava beans.
Combine vegetable oil and shallot in a small saucepan over medium heat and cook, stirring occasionally, until shallot is golden brown and crisp, 10-12 minutes. Transfer shallot to a paper towel-lined plate.
Add dressing to bowl with vegetables, season with salt and pepper, and toss to coat. Transfer salad to a serving platter and top with shallot and bacon.
DO AHEAD: Dressing and vegetables can be prepared 1 day ahead. Cover separately and chill.