targeted performance improvements while maintaining core plan:

1. Spatial Grid Optimizations:

```python
def update_spatial_grid(self):
    # Use direct array operations instead of dict
    # Pre-allocate grid arrays for particle positions
    # Batch update active cells
```

2. Force Calculations:

```python
def calculate_forces(self, particle, x, y):
    # Vectorize neighbor force calculations
    # Cache common force values
    # Use direct array math instead of loops
```

3. Temperature System:

```python
def handle_temperature(self, dt):
    # Batch temperature updates
    # Use array operations for heat transfer
    # Pre-calculate temperature thresholds
```

4. Particle Creation:

```python
def create_particle_circle(self):
    # Pre-calculate circle bounds
    # Batch particle creation
    # Use array operations for position checks
```

5. Phase Transitions:

```python
def handle_phase_transitions(self):
    # Group similar transitions
    # Cache property lookups
    # Batch state changes
```