Logic Pro CPU Optimisation & Bus Routing Fix

Case Study

Optimising Logic Pro CPU Usage for Large Orchestral Mixes

The Client’s Challenge

I recently connected with a professional composer who was in the middle of a critical phase of production. He was preparing to mix a large number of audio stems for an upcoming recording session. We had worked together previously to establish a workflow for importing large quantities of files, where I had suggested using Logic Pro’s “Track Stacks” feature to organise his instruments into folders.

However, as the project grew in scale, a new and severe problem emerged. The client was experiencing frequent crashes and system instability. His project contained a massive track count—potentially reaching up to 400 individual string tracks—and the playback engine simply couldn’t keep up. He was finding it impossible to work without Logic Pro freezing or dropping audio, which was threatening his delivery deadline.

At Audio Support, I often see this specific bottleneck: a creative vision that outgrows the technical limitations of the computer hardware, requiring a shift in engineering strategy.

Session Setup

We established a secure remote connection so I could view his screen and analyse the project in real-time. Being able to see the Logic Pro mixer window and the system performance meter simultaneously is essential for this kind of diagnosis. The client could watch my mouse cursor as I navigated his project, turning the session into an interactive lesson rather than just a repair job.

Diagnosis

Upon opening the Logic Pro mixer, the cause of the crashes became immediately apparent. The client had applied high-quality processing plugins—specifically reverbs and delays—directly onto the channel strip of almost every individual instrument track.

While modern computers are powerful, Logic Pro is not designed to handle hundreds of individual instances of a convolution reverb running simultaneously. If you have 400 string tracks and you place a reverb plugin on every single one, the CPU has to calculate that effect 400 separate times. This redundancy was maxing out his available processing power, causing the audio engine to overload and crash.

The client had read about “stems” and “busing” in theory, but—like many musicians I help—he had gotten stuck when trying to implement these routing concepts in a live, high-pressure project.

The Fix

The solution required a fundamental change to the signal flow (routing) of the project. We moved from an “insert-heavy” workflow to a “send and return” workflow.

1. Implementing Bus Routing

Instead of placing a reverb plugin on every violin and cello track, I set up a dedicated Auxiliary (Aux) Channel. We loaded a single, high-quality reverb plugin onto this Aux track.

2. Using Sends

I demonstrated how to use the “Sends” slot on the individual instrument channels. By turning up the send knob on the string tracks, we routed a portion of their signal to that single Reverb Aux. This meant the computer only had to process the reverb algorithm once for the entire string section, rather than hundreds of times.

3. Creating Summing Stacks

To further organise the mix, we grouped the instruments into Summing Stacks. This allowed the client to process the entire string section as a single unit. For example, we could apply EQ or compression to the “All Strings” bus rather than to every individual file, saving even more CPU cycles.

Additional Support: File Management

During the session, we also uncovered a secondary issue. The client had moved several source files out of their original stem folders, causing Logic to report “Missing Files” errors upon loading.

This required some digital detective work. I used Logic’s Project Management features to search the hard drive, locate the displaced assets, and re-link them to the project. We then consolidated the project files to ensure that all audio assets were stored in the correct project folder, preventing this issue from recurring in the future.

Reflection

This session highlighted a common turning point for many composers. When you are writing a demo with ten tracks, you can put plugins wherever you like. But when you step up to a professional level with hundreds of stems, you must think like a mix engineer.

The client theoretically knew he needed to use buses, but the technical barrier of setting up the routing prevented him from doing so. By walking him through the setup step-by-step, we didn’t just stop the crashing; we made his workflow significantly more efficient. He can now scale his projects up to hundreds of tracks without fearing a system overload.

Closing Thoughts

It is incredibly frustrating when technology gets in the way of a deadline. I help musicians and producers worldwide solve problems like this every day. If you’re struggling with Logic Pro crashes or CPU overloads, I’ll help you find the real cause and get you back to creating.

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