Pdf Merge Taking too long in laravel job

Question

I am merging pdfs . These files could be more than 100 . Now problem is my server only has 1 GB RAM. Server hangs when these merging starts actually this process is working in Job. It works fine on my localhost which has 4 GB of RAM . First thing I want to ask is how I can optmize this process so memory didn't use at once? May be I am doing something wrong in logic . Please Identify that If any

Here is code which is written inside Job handle() function

            $pdfMerger = new  PdfMerger();

            $bulk_pdf = public_path('bulk-pdf-consignment/manifest' . $this->manifest_id . '_.pdf');
            $allFilesPath = public_path('bulk-pdf-consignment/manifest_' . $this->manifest_id);

            // if (File::exists($bulk_pdf)) {
            //     $pdfMerger->addPDF($bulk_pdf, 'all');
            // }
            $filesInFolder = collect(File::files($allFilesPath))->sortBy(function ($file) {
                return $file->getCTime();
            });

            $arr = [];
            $filesCount = 0;
            foreach ($filesInFolder as $path) {
                $file = pathinfo($path);
                $finalPath = $file['dirname'] . '/' . $file['basename'];

                $added =  $pdfMerger->addPDF($finalPath, 'all');
                if ($added) {
                    array_push($arr, $finalPath);
                }
                $filesCount++;
            }

            $merged =  $pdfMerger->merge("file", $bulk_pdf);


            if ($merged) {
                $url = Storage::disk('s3')->url('bulk_pdf_consignments/manifest' . $this->manifest_id . '_.pdf', fopen($bulk_pdf, 'r+'));

           
                Notification_Helper::sendNotification($this->user_id, 'Download Bulk Print Label PDF'.$filesCount, $url,$this->user_type);
            
                if ($this->user_type == 'staff') {
                    $user = Staff::find($this->user_id);
                }
                    if ($this->user_type == 'customer') {
                        $user = Contact::find($this->user_id);
                    }
                    sendEmail($user->email, 'Manifest Consignment Labels PDF ', $url, $attachment = null);
                    File::delete($bulk_pdf);
                    File::deleteDirectory($allFilesPath);
                    foreach ($arr as $file) {
                        File::delete($file);
                    }
                }

My second Question is can I test on localhost by reducing my RAM to 1GB ?