Code run fast on a cronjob but slow with a do_action or ajax call

I am creating several posts from a csv, when I execute the code using a cronjob the operation lasts about 7 minutes, but if I use the code directly in a template, or make a call to do_action or execute the code through ajax it takes more than 30 minutes and sometimes it doesn't even complete (generates a time limit error).

Does anyone know what could be happening?

For the creation of the posts I am using wp_insert_post, update_post_meta and wp_set_object_terms. Total posts created is 6544, when created WITHOUT the cronjob it tends to only create around 3000 +/- before failing

EDIT: Added the code used to create the posts

add_action('import_export_csv', 'import_export_csv');
function import_export_csv () {
    try {

        wp_defer_term_counting(true);
        wp_defer_comment_counting(true);

        // Read data from csv
        $homeUrl = home_url();
        $fileUrl = $homeUrl . '/wp-content/uploads/csv/import_export.csv';
        $csv = array_map('utf8_encode', file($fileUrl));
        $csv = array_map('str_getcsv', $csv);

        $header = true;

        $i = 0;
        $dataArray = [];
        $fullDataArray = [];

        foreach ($csv as $key = $csvRow) {
            // $csvSplit = explode(;, $csvRow[0]);
            $i = 0;
            $dataArray = [];
            foreach ($csvRow as $value) {
                if ($i == 0) {
                    $dataArray['flow'] = $value;
                }
                if ($i == 1) {
                    $dataArray['Reporter'] = $value;
                }
                if ($i == 2) {
                    $dataArray['Product'] = $value;
                }
                if ($i == 3) {
                    $dataArray['HS-Code'] = $value;
                }
                if ($i == 4) {
                    $dataArray['Unit'] = $value;
                }
                if ($i  4) {
                    if ($header) {
                        $dataArray['data'] .= ' . $value . ' . ',';
                    } else {
                        $resetNumCol = $i - 5;
                        $getYear = explode('-', $columnYearValue[$resetNumCol]);
                        $getYear = str_replace(', , $getYear);

                        $dataArray['date'] = $columnYearValue[$resetNumCol];
                        $dataArray['year'][$getYear[1]]['data'] .=  $value . ',';
                        $dataArray['data'] .= $value . ',';
                    }
                }
                $i++;
            }
            if ($header) {
                $arrayHeader = $dataArray;
                $header = false;
                $columnYearValue = explode(,, $arrayHeader[data]);
            } else {
                $arrayValue[] = $dataArray;
            }
            array_push($fullDataArray, $dataArray);
        }

        foreach ($fullDataArray as $productDatas) {
            $productName = $productDatas['Product'];
            $productFlow = $productDatas['flow'];
            $productReporter = $productDatas['Reporter'];
            $productHSCode = $productDatas['HS-Code'];
            $productUnit = $productDatas['Unit'];
            $productYearDatas = $productDatas['year'];
            if ($productYearDatas) {
                foreach ($productYearDatas as $key = $productYear) {
                    $productDate = '20' . $key;
                    $uniqueValuePost = $productDatas['Reporter'] . '-' . $productName . '-' . $productDatas['HS-Code'] . '-' . $productDatas['flow'] . '-20' . $key;
                    $uniqueValuePost = sanitize_title($uniqueValuePost);
                    $productDataString = rtrim($productYear[data], ',');

                    $args = array(
                        'posts_per_page'   = 1,
                        'post_type' = 'product',
                        'post_status' = array('publish', 'future'),
                        'name' = wp_strip_all_tags($uniqueValuePost),
                    );
                    $product_posts = get_posts($args);
                    $generateDate = new DateTime('01/01/' . $productDate);
                    $generateDateFormat = date_format($generateDate, 'Y-m-d H:i:s');
                    if ($product_posts == NULL) {
                        $my_post = array(
                            'post_title'    = wp_strip_all_tags($uniqueValuePost),
                            'post_name'    = wp_strip_all_tags($uniqueValuePost),
                            'post_date'      = $generateDateFormat,
                            'post_content'  = '',
                            'post_status'   = 'Publish',
                            'post_type'     = 'product',
                        );
                        $postId = wp_insert_post($my_post);
                        update_post_meta($postId, 'unique_id', $uniqueValuePost);
                        update_post_meta($postId, 'year_data', $productDataString);
                        update_post_meta($postId, 'data_unit', $productUnit);

                        wp_set_object_terms($postId, $productFlow, 'datatype', false);
                        wp_set_object_terms($postId, $productReporter, 'country', false);
                        wp_set_object_terms($postId, $productHSCode, 'hscode', false);
                        wp_set_object_terms($postId, $productName, 'productname', false);
                    } else {
                        update_post_meta($product_posts[0]-ID, 'year_data', $productDataString);
                        update_post_meta($product_posts[0]-ID, 'data_unit', $productUnit);
                    }
                }
            }
        }

        wp_defer_term_counting(false);
        wp_defer_comment_counting(false);

        echo The file was uploaded and processed successfully;
    } catch (Exception $e) {
        wp_defer_term_counting(false);
        wp_defer_comment_counting(false);
        echo 'Error: ',  $e-getMessage(), \n;
    }
}